Developing 24 stitch optical illusion patterns for use on punchcard machines and more.

I have recently become obsessed with designs that fool the eye in any number of ways, and although knitting them in more than 2 colors is possible, I prefer the ease of only using 2.
Floats are likely to be too long in these knitting patterns for knitting them as single bed fair isle.
Software facilitates but is not necessary to develop repeats, the process may even be performed on graph pater with colored pencils if one so chooses.
Punchcard machine users are not always included in conversations, this post  addresses some ways of developing full 24 stitch designs and performing the necessary color separations for knitting them as DBJ where each color in each design row knits only once.
Brother KMs: punchcards and their use  reviews the basics including DIY development of simple motifs repeated in symmetrical tiled patterns.
The Manual for the Brother KR 830 offers this advice on DBJ knitting: Using lili buttons along with the slip stitch setting in both directions on the ribber carriage reduces motif elongation and keeps the aspect ratio of the planned designs closer to that in the originals than when choosing other DBJ techniques.
Ribber needle tapes are marked with lines followed by spaces. If the start under the first ribber needle on the left is on a blank space on the needle tape, simply end on the right with a needle over a line marking, or the reverse.
I am often asked why in my own illustrations the slide lever on the ribber carriage, a Brother “thing”, is always in the center position.
Reducing variables exponentially reduces errors.
If the lever position is not changed after those first rows or accidentally changed during knitting, the knit gauge will change. An example: working on final projects, more than one student in my knit studio design classes realized only after completing front and back or the second sleeve that the rib with the alternate lever setting not changed resulted in a visibly different rib height in the second piece.
Necessary adjustments can be made in yarn mast and respective carriage tensions, along with yarn choices appropriate for the technique.

ArahPaint and/with/or Gimp with a sprinkle of Mac Numbers have become my preferred go-tos for developing knit designs.
Designing can begin with simple drawings which do not require complex software knowledge and help to build confidence, using the electronic equivalent of graph paper and colored pencils.
Beginning with ArahPaint, with the goal of developing a 24 stitch pattern: load a new square picture, with an odd number of cells, in this case 13X13
Choose from the default palette, or set the number of colors to 3 and adjust the the results to include white, black, and one other clearly contrasting color Draw some starting lines/shapes that can be outlined with single pixels pencils Using the single pixel pencil tool, fill outlines in with color 3 To eliminate double pixels, mirror the image using the 25X13 pngrepeat mirroring using the 25X25 png Using the rectangle select tool, again to avoid double pixel lines, trim a row from the top and the right side of the design the 24X24 cropped result tiled as is with with the palette reduced to black and white The question remains as to how best to knit similar designs on any machine.
The floats are too long for FI, the repeat is best suited for DBJ.
The easiest color separation for DBJ is the one where each color in each design row knits twice.
To have each color in each design row knit only once, electronic machines offer the KRC button. The same result can be obtained in punchcard knitting by custom color separating the design.
When knitting DBJ with these separations, the 2 most common causes of stripes on both sides of the fabric are beginning the preselection row on the right, rather than the left, or as in my swatch, forgetting to push in both slip buttons.
This separation process for me is a very quick one using Gimp, I have not yet sorted a similar one in ArahPaint.
Using color to alpha as described in previous posts, the required files:
24X24 BW
24X48
24X48 color invert
24X4 with the top rows in a color picked from the program’s built in palette. Use Colors, white to alpha, to render the white see through. Copy the file to the clipboard, and use it to bucket fill with pattern  a new 24X49 (col inv png 48+1 blank row at top) bucket filled with the clipboard patternthe pink color to alpha, renders it see through, th last row is cropped, to 24X48, and is copied and pasted on the original 24X48 imageThe proof of concept swatchIf you enjoy designing with pencils in paint programs, the same approach can be used to produce a larger repeat, which makes the illusion more noticeable, ie in this 36X36 design.
Open a new window with an odd number of cells,  ie. 19. Copy and paste the upper left of the design on the new upper left corner, keep filling in linesRepeating the steps described previously, the 19X19 png is mirrored -1 in both directions, and trimmed to a final 36X36 design Modifications resulting in added shapes beginning to appear can be small in developing variations while continuing with the 24 stitch constraint.      Repeating the process, the files in sequence   The proof of concept was knit using the color white for the first preselection row to the right and as the first knit color row to the left, the color inverted version of the original repeat.  The KRC electronic separations are intended to begin with the white pixels in the designs, but the knitter can change that sequence based on their preferred placement of dark vs light colors.
Visualizing the reverse color placement in a knit swatch using Gimp  Mosaic and maze knitting, also known as floatless fair isle, has been discussed in many other posts.
The appropriate color separation shares much of the process with that for DBJ but the starting image is used as is, not rendered double length to start with.
The convention is the same as for fair isle, floats wider than 5 stitches are generally avoided.
In the 40 stitch design, there are spaces as wide as 15 cells with no contrasting color ones, which will be responsible for float formation.
Answering the “what if” question if the 24 stitch design design was used as a possible maze design.
The Gimp process in shorthand While the DDJ separation is used as is, this separation must be rendered double length in order for it to be executed single bed with the knit carriage set to slip in both directions, and color changes every 2 rows.
Using color invert on the final file, reduces the white cell, skip stitch float counts from a maximum of 15 to one of 6. Tiling will check on repeat alignments but has no relationship to the final look of the knit, where the slipped stitches will be gather the knit ones near them. The resulting swatch is highly textured, some of those extra long slipped stitches could be amended by making small changes in the design if it were to be developed further.  

For electronic models, the second 24 stitch repeat extended to 30X30
36X36  

ArahPaint in knit design 4 illustrates a way where following guidelines in Easily generate random weaves it is possible to quickly generate more random DIY designs for use in multiple techniques and stitch counts.

More separations for various knits using Gimp, color to alpha

WORK IN PROGRESS

a caution: 4/26/24 Gimp crashed repeatedly at the step when I tried to copy the brush from the clipboard to bucket fill any images with the pattern. The same reoccurred after an iMac restart and after a Gimp reinstall.
The problems appear to have been eliminated by uninstalling 2.10.36 and downloading and installing the previous, stable version 2.10.34.

Other posts have used the Layer> Transparency> Color to Alpha or Colors> Color to Alpha as part of other menu options, but in the last post and here the selection is the primary tool in developing transparencies.
This design was originally shared in the post: Gimp Update for Mac 3_more on color separations, where the goal had been to reproduce a published 12X18 chart. 

The PNG matching the chart on the right may be used in several ways. On electronic machines, it would be ready for knitting using both the color reverse and the double length buttons if planning to use tuck or slip settings with color changes every 2 rows.
Punch card machine users must punch the color-reversed file and set their models for double length,  but punching out the lengthened version 36 rows in length provides enough for the card to advance properly in the drum and makes correcting errors easier.
Revisiting the photograph of a swatch using the design using wire and chenille in half, and wool rayons in the other, I was bothered by the breaks at the midline of each repeat. Tiling the first design provides evidence of the area at issue, led to adding/subtracting a few pixels at a time, seeking slight changes, and ending with two final variations:  
Variation 1
Variation 2  The Gimp color to alpha process in RGB Mode for mosaic knitting: file 1 is opened. Several new files may be opened in sequence for altering, copying and pasting onto each other, with steps performed as a continuous process or with saving results and returning to them in separate steps    file 2: its color reverse
file 3: a 2-row brush with white color to alpha file 4: file 3 used to bucket fill 2 with pattern file 5: magenta color in 4 to alpha

file 6: file 5 copied and pasted onto file 1.
Change Mode to BW Indexed
file 7: file 6 color-reversed for knitting with the tuck or slip setting,   will need to be doubled in height for color changes every 2 rows using the double height button or use the file rendered double height to 18X36 pixels using Image> Scale in Gimp The proof of concept:  1: The StitchWorld #548, 24X40 pattern was also used in that post, it is suitable for punchcard machines as well  Using bucket fill with pattern makes the process faster than using the pencil tool to fill in color manually before converting colors to alpha in separating it.
While mosaics are processed in their original length, DBJ files are doubled in height.
2: the file is scaled to 24X80 3: and color reversed 4: a 2-row brush with white color to alpha 5: is copied to the clipboard and is used to bucket fill with pattern the color reversed image   6: the cyan is rendered transparent by using color to alpha again,  7: and 6 is copied and pasted on #2, the first 40X80 image,  8: and doubled in length to 40X160, it is exported as a BW PNG for knitting as DBJ. The results with both methods match.   Each color in each design row will be knit twice.
The method for emulating the separation that is built-in in Japanese electronic models, where each color knits once reducing elongation is a bit more fiddly to perform.
Charts from left to right:
1: the scaled 24X80
2: is color reversed
3: a new file, 1 row longer, 24X81 is opened, 2 is pasted onto it, leaving an all white pixel row at the top of the design
open a 24X4 row file, with two top white rows to alpha, use it as brush to bucket fill 3 with pattern
4: magenta color to alpha
5: crop that last blank row from the file, now 24X80 once more, copy and paste it onto 1.
The green grid is to differentiate this result from the one obtained in the other post, shown at its right
Change image mode to BW Indexed, export as png for knitting.
The proof of concept Returning to the repeat used to produce this punchcard the very low tech wayRepeating the steps used for the last designWorking in RGB Mode the 24X6 starting repeat was lengthened X2 to 24X12, and colors exchanged to black and white, because using color invert in RGB mode introduces a different palette confusing the process.
1: To produce the separation for a full punchcard, the image is tiled X3 in height to meet the 36 row minimum card length and 2: is copied and pasted on a new file of the same dimension, and color inverted 3: the color inverted file is copied onto a new 24X37 one with with an added blank row at the top 4: a new file 24X4 is opened, the bottom 2 white rows are rendered transparent using color to alpha, and saved to clipboard 5: to be used to bucket fill in pattern the color inverted 24X37 image (3) with pattern  6: the pink color is now rendered transparent as well using color to alpha crop the last blank row, the file will now be 24X36 again,
7: copy and paste it on the first image for the final KRC emulating png, check the file mode, and save as indexed BW for use in electronic models. When color inverted
the repeat matches the punchcard separation. It is possible to magnify, screengrab, and scale the pngs to print templates for counting stitches or even tracing to mark cards prior to punching holes.

Color separations for larger scale mosaics and mazes

There are generators online for many generators to aid with knitting design. In 2015 I published a post on working with generated mazes: Gimp charting 1
The mosaic and maze graphics prior to their color separations are not suitable for fantasy fair isle double bed knitting as a shortcut. There are simply too many vertical white pixel rows begging for carriage jams no matter the machine used. The same long lines of black or white cells make them unsuitable for traditional fair isle knitting as well.
Visual clues are helpful as steps get navigated. In small-scale repeats, a different option from the method that follows is to begin with a file previously used and separated, magnified to 1800X.
1. using the rectangle select tool, begin on row 1, extending handle outside the image, I work from left to right
2. hold down the shift key, and continue selecting every other row. As each row is selected, it is outlined with dots. The handles to the right and left of that row serve as guides as to the last row worked, moving up as separation progresses. Clicking on the rectangle select tool at any point fixes the layer, and the dotted lines will disappear. The process could be performed in steps, with guides placed prior to color inverting the previous steps in the sequence and moving onto the next. The guides remain until they are removed by clicking on the check mark beside show guides, or with the Image / GuidesRemove all Guides command.
In large designs, I would guess this may be more easily error-prone than when using layers.
3. after each pertinent row has been selected, choose the color invert option, and save the resulting file. The first step is completed in the separation.
The file then needs in turn to be color-inverted and lengthened X2 prior to knitting. The result matches the separation in the previous post.   Holding down the shift key when using the pencil tool on any image produces very different results.  My samples continue to be knit on the 930 using img2track, a download program I find reliable and easy to use. The only errors in programming I have encountered were due to operator errors, not software ones.

Since 2015 working with larger images has become far less daunting as my methods for color separations of mazes and mosaics have evolved.
Laura Kroegler’s online Mosaic Pattern Generator is still available. Returning to it, and using these parameters the pngs were downloaded both in red and then again in black and white. A 38X38 stitch repeat was isolated, and using Layer/Transparency/Color to Alpha a knittable mosaic design was obtained which, when knit, would require elongation X2 for color changing every 2 rows The last file, doubled in length to 76 rows in height, requires no further processing The separations are achieved now in just minutes.
The proof of concept swatch: when using repeats that are so much wider, one must commit to far larger swatches to test them. In addition, the placement in the final piece may matter with shifting the pattern to highlight a preferred center, here the machine was allowed to place the design as a simple overall one on 78 stitches by 116 rows. There are droves of inspiring large-scale mosaic crochet images published nowadays, which led me to wonder about DIY similar large graphic mosaics in machine knitting.
I performed the first color separation with shortcuts, used mirroring the cleaned-up repeat, did not verify each step with tiling, and committed to knitting a test swatch. A 68X136 repeat X2 in width and at least with 40 more rows in height, produced a 16X24 inch test swatch, wherein a couple of missing pixels became noticeable.
The swatch was also knit using slip in both directions on the main bed, which produces a narrow, short fabric as opposed to wide and also short when using the tuck setting. Back to the drawing board.
The initial approach is similar to that used in creating mock filet crochet shapes on the machine.
With present tools the results process is easy and quick: to begin with, choose any symmetrical design where the shaping of the motif occurs in single rows, this one measures 23X23  scale the file X3 in both directions to 69X69 save this brush to use later for bucket-fill in the design.     Choose fuzzy select by color/black, each shape will be surrounded by a dotted line bucket fill the selections with the saved pattern click on rectangle select to fix the layer, work on and clean up the repeat, and check a magnified version for any missing or misplaced pixels.  Save the png. for reference before continuing to work. Make one of 2 choices. If the goal is to place a motif, and to add borders or horizontal additional design stripes, create a new canvas, larger in size than the above, fill it with the same pattern, and then Colors/Invert.  Click on the rectangle tool to fix the layer.    Change the white color to alpha in the previously processed snowflake, click on the rectangle tool again copy and paste the file onto the color-reversed grid, and click on the rectangle tool.  Check the pasted image visually, and continue adding any other designs.  If the goal is to produce an all-over design, crop the shape on the dotted ground, and save it as a 69X69 repeat. Pasting the original on an equal size color reversed dotted ground does not work.  Tiling the result of the cropped repeat will show the need for cropping it by one row at the top and one column to the right.   The resulting repeat, 68X68 tiled X3 in each direction for a visual check.  Using the process previously described
1. open the 68-stitch file in Gimp, and magnify it to at least 800X for a visible grid
2. open file/new, equal size and magnification
3. copy and paste 1 on 2, click on the rectangle select tool
Colors/invert, click again on the rectangle tool or anywhere in the work window 4: magnify further if needed. Using the pencil tool fill in every other row beginning with row 2 in a contrasting palette color, and click on the rectangle tool 5. Layer, transparency, color to alpha, as described in the last post, click on rectangle tool 6. Copy and paste this result onto the 68-stitch file in the first window, there will be lots of dotted lines onscreen  Click on the rectangle select tool to paste the image in place. Since those large areas of white will be knitted in a tuck or slip fabric, the above result needs to be color inverted. If used as is, set the machine’s built-in double-length function.  Doubling the length of the file prior to the download to km Part of the view on the img2track screen for the 68X136 file ready for download. Committing to proving the concept:  Using the same approach of tripling the original, here the repeat was used in an attempt to render a larger-scale mosaic. The process becomes fiddly because using the fuzzy select tool and then the bucket-fill-in pattern does not work cleanly on areas that are only 3 pixels wide.
That said, it is possible obstinately, in stages, to get from this, 36X54 To a 36 by 56 mosaic
A last edit Perhaps falling in the category of “don’t have to simply because I can”.

Images at this stage of the process may be knit double-bed as a “fantasy fair isle” with no further separation.
On an electronic machine, download the repeat, program it for the number of needles in use on the top bed, and select the KRC separation button.
The first preselection row will need to be from left to right.
The main bed is set to tuck in both directions, the ribber to N in both directions.
There will be lots of non-selected needles tucking on rows with large numbers of side-by-side white cells. Because the fabric is being knit using every needle on both beds, each main bed tuck loop will have a knit stitch on the opposite bed anchoring it down. Those rows will appear more compressed, producing narrower horizontal lines The yarns used were very thin single strands of  2/28 at tension 4/3. The result is a very lightweight and loose knit with lots of drape. The 72 stitches by 140 rows swatch measured 16 inches in width by 10 rows in height. Perhaps a good method for summer shawls, worth exploring in thicker yarns for blankets. A closer look at the structure:  A larger BW design was processed using no modification of the original 75X71 motif. When using Gimp/File/Save, the result is a .xcf document similar to PSD files in Photoshop. It will store layers, transparency settings, and more information associated with and parts of the same project. Note to self: before deleting the .xcf make certain that at least the final png has been saved.

If one is familiar with image processing and fond of the maze appearance in designs, there is a font to try: Mazeletter
The downloadable associated documentation and source for inspiration: http://mazeletter.xyz/Mazeletter.pdf.
A very quick random type sample rendered with no advance planning: 

Another, mosaic4way, is potentially usable for single bed fair isle or dbj.  The drawback has been that my sample pngs for both were created in RGB mode, and conversion to BW or scaling loses details.
It is possible to begin on an all-white canvas, set the mode to indexed to start with, type text, merge layer down, crop to content, and have workable indexed black and white knittable results, but the degree of success appears to depend on the font size used.
Another thing to investigate 😉

Gimp Update for Mac 3_more on color separations

The latest version Gimp Download site
I am self-taught. As I learn new tools, my workarounds may be convoluted and more complicated than they need to be and evolve with time. I do not delete older posts or their content, but do occasionally add links to later posts or dated notes.
I began designing and charting in the days of having to draw on graph paper and cutting up results to see if the repeats would tile properly when knit, or to place them for alignment variations such as half drop or brick.
Scanning amounted to tracing with a marker onto blank sheets of acetate or tracing paper.
The availability of commercial acetates for purchase at seminars, printed in pairs of matching horizontally striped sheets in lines separated in a variety of widths, offered an advance in scaling designs to a knit aspect ratio. Copy machines became useful friends.
DBJ designs in the punchcard studio, when I began teaching, were accomplished at first with the use of cards themselves as templates and overlays, involving a series of time-consuming methods for each type of separation ie.  So many such processes are now nearly instantaneous by comparison.
Earlier this year the post Using Layers in Gimp for color separations explored several fabrics beginning with B/W motifs.
Sometimes lightbulbs go off leading to other ideas for achieving results in quicker or easier ways.
This color separation method for mosaics continues to use Layers but in a different approach.
A spreadsheet may still be used if preferred to draw the initial draft of the design, working in black and white only would be fine, and the import could then be processed in Gimp.
Mosaics and Mazes are generally knit with color changes every 2 rows using either the slip stitch or tuck carriage setting in both directions. Beginning with any DIY or published design, to knit the motif using the tuck setting, there are basic rules to remember.
This illustrates possibilities using a random 6-stitch repeat, A.
If the plan is to set the knit carriage to tuck in both directions, the design would need to be color-reversed to BThe white cells in B represent loops held on corresponding knitting machine needles, the limit in Japanese standard machines is often 4. Black cells represent knit stitches, generally seen in groups or on either side of tuck stitches/ white cells, to anchor the loops down for proper stitch formation. There are some infrequent exceptions to that rule.
When uncertain as to results in developing DIY designs, begin with a published repeat to build up confidence. This is a hand-knitting resource for endless inspiration, no separations are provided in the book text.  There are always many ways to achieve the same task depending on the specific program used, one’s level of skill, and individual thought process.
This method uses multiple windows in progression.
When starting out, save the result in each step for added practice or in case any step is accidentally deleted.
This is by Kathleen Kinder, published in Floatless Fair Isle, p. 87 Though the final designs are saved as black and white pngs or bmps, to work using colors in separations, the mode needs to be set to RGB. For very small repeats, use view, show grid,
magnify 1800X, type in a number for a preferred value,  or use the command key in Mac and the scroll wheel of your mouse to do so. Using the pencil tool draw the repeat in black and white Selecting file, new, open a canvas in the same size and magnification, with each step a new icon appears at the top left of the Gimp window to select any file, simply click on the corresponding icon, use Edit Copy or command C, and then edit, paste or command V to place files onto new selections.
Copy and paste the first image onto the blank canvas and colors-invert the result  To draw straight lines on a Mac, use the pencil tool to place the starting pixel. Hold and drag the mouse to the desired endpoint. As this is done, a guiding line will appear. When the endpoint is reached and the mouse is released, that line disappears and the selected area will fill with the chosen color.
When using the 2-pixel brush, the mouse must be placed slightly into the second row of cells before dragging it for the line to remain straight and in the proper rows. If an error is made, choose Edit, Undo, to eliminate any step.  Continue to work on the color inverted file, and beginning with row 1 fill in every other row with a distinctly different color. To fix any layer before continuing, click on the rectangle select tool, and then again anywhere in the work window.
Getting rid of the red: this will be the immediate appearance of the image in the window, disregard it.
Right-click on Color/white, choose the foreground or background color or left-click on the Color bar, and click again to choose the color from the palette window. Choose rectangle-select cool, click on the result to fix the image, and the color window will disappear. The result: Copy and paste the file onto the initial image, there will be dotted lines upon the placement,  Click on the rectangle tool again, and then in the work window for the final png repeat. Change the image Mode to Indexed BW if its end use is a download to an electronic machine  Why is it different than the Kinder repeat? It is easier in drawing to color in white squares as opposed to black, so the repeat in the pub is the above, color reversed.  Punchcard machine users may mark the black squares and then punch all others.
The last step: if colors are to be changed every 2 rows, remember to use double length or to program/punch the last png double length.  An illustration for the full double-length punchcard repeat. The above, 12X36 repeat was color reversed and tiled twice to meet the 24-stitch width requirement. The 36-row height also meets the minimum height requirement for punchcards to roll in continuous patterning.
Mark the black cells in the image below on the card, and punch all the white ones. These fabrics are often more interesting using the tuck setting than the slip stitch one.
I have a lifetime supply of copper yarns from my jewelry-making days. This repeat is more a maze than a mosaic. Using a fishing line or wire can sometimes also produce interesting effects.
The blue yarn is composed of 3 strands of 2/48 cashmere/ wool.
The wire is a 32 gauge coated copper magnet wire which tends to flatten the final knit. On the machine, it is hard to recognize repeats due to the very short floats, and the unusual fiber rows can appear to be see-through Using a light color wool rayon as the second color. Using a separated 16X16 repeat from the 2020 post to knit a swatch for Instagram, I noticed a solid 3X3 block in the center of one of the shapes. Because the wire is see-through to some extent, the white stitch floats behind the blocks are noticeable. The copper wire used was 40 gauge, 3 plied. The higher the gauge number the thinner the wire strands, nearly invisible when threaded and while being used. Because the knit tension was as tight as possible, the stitch definition is lost in a few spots.
The original design motif, on the left, was missing a white cell in the location of the red cell. It was quickly converted using only Gimp.  Comparing the old repeat to the new, that problem pixel may easily be located. The corrected file before lengthening X2,  double length  Proofing a pattern is best done using comparable weight, familiar yarns. Here thin poly and 4-pound fishing line are used as the second color It takes a bit of squinting to see the match.  Testing the same repeat in more “friendly” and equal-thickness yarns This 24X28 repeat from the earlier post is reworked in this method repeating the process described here, it took longer to render the repeat than to perform the color separation.  The tiled alignment check
The steps are in sequence and produce a result matching that achieved in the previous post. A reminder: step #6 result would need to be doubled in height, whether by altering the file prior to download or by using the built-in functions in the machine after the download. The theoretical color separation to knit the mosaic as DBJ where each color knits twice, the repeat single length, 24X56 double length, 24X112

Double jacquard using punchcard machines shared manual methods for including one avoiding the elongation by matching the electronic built-in KRC color separation. Using Layers in Gimp for color separations introduced an approach using only Gimp.
There are times that the 2-color separation for DBJ which knits each color in each design row twice is necessary for the intended knit technique.
When testing new methods, one may begin with files that have already been proofed. This file is created so no elongation is required, beginning with the shape elongated X4.
From the layers post, the double-length separation where each color in each design row knits twice Duplicating the result using layer/ transparency  Longer repeats can become more complicated to separate. Testing the results by necessity requires larger swatches.
Using Stitchworld #548, a 24X40 repeat, as with mosaics1: draw the desired repeat in Gimp
2: when the drawing is completed, tile the repeat to check alignment, save the image if desired, or discard it
3: in the original window, scale the image to double its original height, now 24X80
4: using file, new, open an image on a white ground in the same size and magnification, a minimum of 800X, with grid view, as the first window
color invert
continuing on the same image, changing magnification as needed for ease of visibility ie 1800 X, choose a palette color, and using the pencil tool fill in every other row beginning with design row 1 using it
5. using color to alpha will remove the blue color in this case, and the image will change in appearance, the blue is now transparent. Copy the result.
6: use the second image, and paste it directly onto the one in the first work window.
For the repeat to knit successfully as DBJ, the resulting  24X80 file will need to be lengthened X2 to 160 rows in height for accurate patterning to occur. The design lengthened X4, using a 2-pixel pencil beginning on rows 3 and 4,
produces a 24X160 file that requires no elongation.  In this DBJ version, the first preselection row is made toward the color changer, followed by color changes every 2 rows.
My proof of concept is knit with the knit carriage set to slip/slip and the ribber setting left to N/N, creating long stitches.
The height of the design, any bleed-through, elongation, drape, and stretch, are variables influenced by carriage setting changes on either or both knit and ribber carriages.
By default, DBJ knitting requires many more carriage passes than 2 color patterns knit single bed as fair isle.
My swatch does not begin at design row 1 because I forgot to set the knit carriage to slip after the first preselection row and color changing on the left.  Scaling the knit for a sense of the degree of elongation The above separation is the default one in Passap knitting machines.
Japanese electronic knitting machines perform the separation where each color in each design row knits only once automatically by engaging the KRC function.
Punchcard users can achieve the same results for repeats that meet the width constraints using a maximum of 24 stitches or factors of 24 in width.
The separation where each color only knits once from the layers post began with the result where each color in each design row knits twice: My first effort using layer transparency to separate for each design row color knitting only once begins with the double length separation opened in Gimp, not necessary as seen in notes that follow.
Using the pencil tools, marking begins on the second and then even numbered design rows.
When # 5 is color reversed, it matches the separation using layers in the above far right  Using the same concept, the first test began with the separation already completed for the repeat that would knit each color in each row twice.
Toggling magnification helps to make the height of the repeat manageable. Errors are easy to spot and correct if noticed early, a few rows of pencil marks can simply be undone. Save the final png, also 24X160. The separated design is suitable for punchcard machines, my swatch is knit on a 930. Since these separated designs are programmed as fair isle designs, there will not be any color change prompts provided by some machine models.
The first preselection row, as when using the KRC function, is made from left to right. The knit carriage is set to slip both ways. The ribber carriage is also set to slip both ways on an even number of needles, and lili buttons are in use. The visual difference in scale between the two different techniques and color separations.  The simplified method begins with the original design scaled X2 to 24X80. The 2-pixel pencil tool is used to mark the resulting design beginning on rows 2 and 3, skipping the next 2 rows, and repeating the process
Committing to a larger test swatch: The repeat though successful in this case is different from half the first one obtained the long way, the concept merits testing with other motifs.   Years ago I shared the way punchcard knitters may create a DBJ card using a series of templates. The starting 8X8 design was often used in my 2 color DBJ posts. On the right, it is repeated across 24 cells, as it would be in a punch card.  Using layer/Transparency/Alpha the same results can as when using the card templates may be attained in just minutes. Here each color in each row would be knit only once:  In this case, the final result would need to be elongated X2 in order to knit each color in each design row twice. This separation requires no elongation. If the plan is to print a template to aid in marking a card prior to punching, one way to determine the required template size is to measure a punchcard with a ruler in mm.
The width of the card is fixed to a print width of 108 mm since the card will always be 24 cells wide. No calculation is required.
In height, the 60 rows on the factory blank card measure 300mm, 5mm for each cell.
I cropped the chosen image to the top 39 rows and scaled it to 108X195 mm.
(39X5).
When printing on US letter size, with no adjustments other than to the image, the limit appears to be no more than 45 rows per page. I was not able to print directly from Gimp.
The file, exported, opened in Preview, and then printed, is shown with a card superimposed on the printout over a makeshift light box, ready for easy punchcard marking even though the printed cells were not all of the same ink density.   2024 the subject of elongation in DBJ designs recently made the rounds in forum again. I was not quite sure where to share this, settled on here
Vertical striper backing on Brother machines is rendered possible by manipulating ribber needles in conjunction with the use of lili buttons.
This swatch uses the same 40X44 pixels design The tension and yarn selection choices remained fixed.
1: conventional striper backing, with the ribber set to knit in both directions
2: half striper backing, with the ribber set to knit from left to right and to slip from right to left. In this technique as the carriages move from right to left, floats will be formed on the top bed. As larger number of needles are knit on either bed, the tension should be adjusted accordingly, here it was not, resulting in those dropped stitches. The floats peek through behind the resulting hole.
3: the traditional birdseye backing, resulting in the narrowest portion of the swatch.

 

 

 

ArahPaint and Gimp in knit design 3

Previously published:
ArahPaint and Gimp in knit design 2
ArahPaint meets Gimp in knit design 1

Subsequent posts on using Gimp Layers to process images:
Using Layers in Gimp for color separations
Layer/Transparency/Color to Alpha Gimp Update for Mac 3_more on color separations

Gimp allows one to work on multiple images with only a single window open, left mouse clicking on any one of the images will bring it into view for editing. In the dark theme, it is hard to see the difference, but a lighter border actually surrounds the active image distinguishing it from the others, outlined here in yellow In Arah, multiple windows may be opened at any one time, and left-clicking on any one of them will bring it to the front for editing.   When working using the same file in more than one window, the degree of magnification needs to match in each.
Spreadsheets and paint programs may be used to achieve color separations for designs intended for specialty fabrics, many worked on the double bed.
Two places to begin exploring them here are for knitting single-bed mosaics and double-bed jacquard in its form where each color in each design row knits twice.
It is unlikely to happen often in knitting that more than 6 colors are used in any one fabric except perhaps in an elaborate color-changing fair isle.
The palette that appears in Arah when opening a new file is random, as seen here when two new files of the same size are loaded  If one’s preference is to reduce the number of colors, the specific number may be set by choosing from the colors menu, editing the number identified as that for the working palette, changing it to the new value, in this case, 6, and the palette reduction occurs as seen in A. For most knit repeats a black color is handy, any one of the 6 colors or more may be adjusted as described in the previous post, seen in B, where black has been added, replacing the color in position 1. More Gimp information: https://docs.gimp.org/2.10/en/gimp-palette-dialog.html
Some of the related content in brief: the former versions of GIMP had a “Save palette” command. Palettes were stored in a specific folder via the preferences pane. Easy to do and manage. It no longer exists.
To save the palette of an image, indexed or not, you must now import it from the image.
The “Palettes” dialog is dockable: from the Image menu, select Window, Dockable Dialogues, Palettes.
A few dozen more or less randomly chosen palettes are supplied with GIMP.“Import Palette” allows you to create a new palette from the colors in a gradient, image, or palette file.
Right-click in the space to the right of the illustrated palettes to call up the import option, or for palette editing. It is not necessary to index the image, this image was used in RGB mode. A palette name can be assigned, and if previously used, a number will be appended by the program.
The number of colors: the default is 256, you can set the number to any you choose. Gimp will try to create a palette by spacing the number of colors evenly across the range of the gradient or image. Each screengrab in the top row shows the initial selections for gradient or image, and the second row of screengrabs notes other changes made when choices were available and the results. White dots mark selections as seen while using the program.   Using the same image, indexed to 5 colors, the custom palette is rendered in a one-step process. The gradient seen in the first position on the top left was randomly assigned by the program and does not influence the results. The Columns selection number settings only influence the way the palette is displayed and have no effect on the way the palette is used. The lower the number, the larger the display size of each color unit.
Double-clicking on any palette color will magnify the palette view on the theme color background. Left-clicking on any color makes it available for drawing, the selection will have a dotted bounding line and the selected color will be assigned to the foreground position,  Right-clicking on a color results in these options.  The imported palette will be added to the Palettes dialog and is automatically saved in your personal palettes folder when you quit GIMP so that it will be available in future sessions.
In Arah, the color palette will always display the colors of the active layer. The working image contains colors intended for use in my designs.  In addition, please see the note from the developer in the comment at the end of the post.  The palette tools: A: if you press this icon the program will underline the colors actually used in the image, since all colors are used in this case, each color is underlined in either white or black in this instance  D: adds color(s) to the palette  B: removes unused colors in the above palette, it would restore the original colors
C: removes duplicate colors, not applicable in this instance
E: removes the last unused color, will not work if all colors are used.
Changing color positions in the palette: to switch the position of two colors in the palette, click the chosen color in the palette, move the cursor to the color you want to switch the position with, and press the left mouse button while holding the Ctrl key on the keyboard. In this instance, the color was duplicated in the new position.  Knitters designing for dbj are likely to work with a limited range of colors, often 3 or 4 max, in specific palette ranges to ready images for download.
If color separations for 3 or more colors are done in shades of grey in terms of technical details, you need a pattern image that is 8-bit greyscale, with each color in a range of 8-bit values. So for 4 colors, it would be 0-63 color 1; 64-127 color 2; 128-195 color 3; 196-255 color 4.
Binary images have only 2 possible intensity values, normally displayed as black and white with values of either 1 or 255 for white, and often 0 for black.
That convention may have led to the selection of white as color 1 in automatic separations such as the KRC Japanese one, where white is selected first. In a greyscale or color image, a pixel can take on any value between 0 and 255. Designing for fair isle, or when attempting to visualize and illustrate slip and tuck fabrics with frequent color changes, more colors may be required even though the final download will be in black and white. There is a quick way to add random colors assigned by the program and based on the initial palette: The magic wand tool allows you to work on consistently colored areas without having to select and outline each.
To alter a single color using the bucket tool, click on the wand, then on the color single color area you wish to change, it will become outlined by bounding lines.
Click on one of the colors in the expanded palette, and it will automatically appear in the foreground color position, and it may then be used to bucket fill the chosen area. Flatten the image using the merge-down tool.
If the foreground color, in this case, white/0, needs to be changed, in order 
to choose all pixels in the foreground color, click on the wand, and use Tools > Select by color or Shift+W. This function works only on 8-bit pixel images. Click on the color you wish to use to replace the ground, and bucket fill with the newly selected color. Flatten the image using the merge-down tool.
Changing multiple color blocks in the same color could be selected by the tool, but filling each of them one at a time was required.  In Gimp a similar tool is the fuzzy select, which also allows for changing the color in a selected area or for selecting and changing all pixels in that color. Selected areas will also be outlined in dashed bounding lines. Bucket fill may then be used to replace color(s). The option is offered to choose either foreground or background for the fill.  2023 in Gimp 2.10.34 use and hold the shift key prior to selecting and using the bucket fill tool to change all the areas outlined by dashed lines. The bucket-fill tool itself now works again on any area with a defined boundary, no other, following action is necessary.

Click on the rectangle select tool and then on any spot in the work area or on the image to set the image. The dashed lines will disappear.
In terms of saving the palette in Arah for future use, I saw no specific directions in the manual.
The color palette displayed is always the one used in the active layer. As a workaround: open the image, and the associated palette will be displayed. The repeat begins drawn 24 pixels in width, by 24 in height.
Select clear from the edit menu, or bucket fill area with white
If the size of your intended drawing area is different, choose the option Resize Image from the Image menu. With the chain link intact, the new canvases are created keeping the aspect ratio. Enter a new value for width/height, hit return, or move the cursor to the alternate value, and its number will automatically change to a matching one. Click OK to use the new canvas, or reset if you wish to return to the original 24 by 24 pixel one for a different edit.
With a broken chain link as one of the two values is altered, a preview is available. If both values are to be changed, break the chain link, enter the two values in turn, and a preview appears for each step. Ok is used again prior to saving, or choose reset to return to the previously used setting. Color separations can make specialty fabrics possible to knit which are outside the possibility of doing so simply by changing cam settings. Two instances are mosaics and DBJ where each color in each design row knits twice. Separating each may be done in two ways. The first method, convenient for longer repeats, requires that the result be elongated X 2, whether in the repeat design software or after download to the machine or using the elongation X2 function in the punchcard models. For illustration purposes here I will be working to create files that do not require elongation.
Mosaics and Mazes are constructed in similar ways and are sometimes referred to as floatless fair-isle even though technically speaking usually 2 stitch floats do appear on the purl side in the alternate color used with each color change.
Many such repeats may be knit using both the slip and tuck settings, the latter is the more interesting of the two on the purl side.
When learning structures it may be worth beginning with a published design.
Kathleen Kinder decades ago published two books, one with 24 stitch repeats, the other with 40 stitch repeats, with the separations included as well This, by Barbra Walker and intended for hand knitting, offers a huge library of designs for inspiration and conversion Following specific rules it is also possible to develop DIY repeats from scratch. That said, the repeat used in this blog post happens to have a known value of 12 pixels by 12Magnification in Gimp is achieved by selecting or typing in new percentages at the bottom of the window.
Entering and exiting the full screen may be controlled via the view menu To exit, it right-click at the very top of the window to expose menu options and select deselect full screen.  In Arah, if you press any number from 0-9 on the keyboard, you will change the zoom directly to that level (1 means 100%, 6 means 600%, 0 means 1000%). The plus + and minus keys- as well as the magnifying lens icons, will zoom in and out To use the entire space available in the window, choose Fit to Window from the view menu or select Ctrl+zero.
If working in more than one window this option makes repeats the most visible, scaling back can be done by counting the number of selections, helping to match the new picture magnification to the first.
Press the escape key on the keyboard to return to the original 100% view.
To work using the full screen, select the option from the view menu. To exit, right-click at the very top of the window to expose menu options, and select exit full screen Separating the design: ultimately the planned final graphic repeat would be a BW png used for electronic download, programmed as a fair isle one, but knit using tuck or slip settings, it may be drawn initially using only in those 2 colors. Black may need to be added to the palette selections.
One may always draw on a large canvas and then crop as needed, but as a starting point, it may be easier to simply match canvas size to the published repeat being used.
It is handy to have an extra column to help track image processing during the separation, the repeat above is identified as being composed of 12X12 pixels, one could begin with a 13X12 canvas.
A second way to provide the 13th column is to work using 2 windows, matching magnification,  and the second with a different, larger pixel measurement than the first. Copy the contents of the original work area and paste them into the larger canvas in the other window. Crop to new size if necessary.
To illustrate the two-window process, here the original BW repeat has already been drawn and elongated X2
A. Use the rectangle-select tool to capture the whole image in the first window, bounding lines in the colors of the palette in use will outline the selected area
B. Use the edit menu or command C to copy the selection, edit paste, or command V in the new window to place it.
When pasting on a different size ground, the bounding lines will also appear in the new image, the contents remain moveable,
C. Place the selection where desired on the new canvas,  when satisfied use the X, merge down tool to flatten it.
The quicker method begins with a canvas one pixel wider than the repeat, 13X12.
Adjust magnification, for comfortable viewing in the editing process.
View: show grid 2
Colors: set the number of colors to 6, and adjust the #1 color to black, white is in position 0 in the palette by default
Activate the pencil tool, and draw a vertical line on the far right in an easy-to-see color choice other than white or black
Using black, fill in pixels for your first draft of the pattern repeat
Image multiply YX2, resulting in 13X24
Using the pencil tool fill in the first 2 design rows followed by every other pair with white. Magnify image A to a comfortable work viewing size.
B and C: using the rectangle select tool, with the left mouse button, place the pointer on the purple pixel, drag the mouse across each pair of marked rows, release the mouse, and use Command I to color invert, and merge down to eliminate the bounding box.
The purple pixels will change color as well, making it easier to track what rows have been altered already.
D: crop the image, removing the row with colored cells for the final repeat
If for some reason you are processing an image that is color reversed, the steps are identical, but tuck or slip stitch fabrics, black pixels or punched holes knit, white pixels or unpunched squares tuck or slip. For this reason, the cropped final result would need to be color inverted prior to knitting or punching holes. This separation for 2-color DBJ results in its potential use in many fabrics other than DBJ and may be performed by some programs used to download multiple color patterns to the machines prior to knitting the fabric. One such fabric is drop-stitch lace.
Punchcard machine users would need to separate the colors manually, or if Dak is available, the separation may be done using the program and a corresponding template may be printed as a guide to punching holes.
This method is the automatic default one for any 2-color DBJ knit on the Passap.
Each color in each design row will be knit with each pair of consecutive color passes. Completing one design row containing 3 colors will require 6 carriage passes, 4 colors 8, and so on.
The built-in color separation in electronic machines wherein each of only 2 colors in each design row knits only once does not apply when using more than two colors,  though it is possible using Dak or by downloading a special card reader technique to program separately from the design when using the Passap E6000 in addition to the pattern repeat.
This separation of a 2 color pattern results in an elongated version of the design regardless of any dbj backing used.
Begin with a 2 color image,  an extra column of pixels is added here as well:
A: multiply YX4 to 13X48
B: mark alternating pairs of rows in the extra column with a contrasting color
C: following the color cues on the far right column, on rows with no added color use the pencil tool to replace black pixels with white, leaving only the orange cells
D: on rows marked with the third color replace the orange pixels with white, leaving only the black pixels
E: crop the image eliminating the extra column
adjust the remaining orange color to black
index the result to B/W, and the image is ready to save and use The difference between single repeats for each type of fabric, no further elongation is required. A: mosaic, B: DBJUsing layers in Gimp opens up the possibility of several color separations for fabrics using only 2 colors.

Both img2track and Ayab are capable of opening 2 color images.
In img2track this is what would appear, after the download the KRC function needs to be activated in the knitting machine.  Ayab: the repeat should be programmed in width equal to the number of needles planned to be in use. The color change happens as the file is loaded into the program, the ribber classic option is used to render results that would match the KRC knitting machine selection after an img2track download. Here the repeat is also tiled in height.  My personal preference is to work with images designed in black and white. With the 910 presently stored, my blog swatches are knit on a 930 using img2track.

A note for Mac users like myself using desktops with the M1 chip and Mac OS Monterey. Img2 track requires an FTDI driver for its download cable, on June 6 finally released a beta version of a more recent driver, I do not plan to install it at this moment, function in the upcoming Ventura OS would be unknown.   Ayab does not launch automatically. These are the steps necessary to run the program, following suggestions by Adrienne Hunter via the Ayab FB group:
open a Terminal window (Applications/Utilities/Terminal) and type these two lines:
cd /Applications/AYAB.app
./Contents/MacOS/AYAB
The app may also be found and then opened via using Spotlight search if you prefer  Once the program is quit unless you choose to keep the terminal icon
in your dock, it will disappear and the above process will need to be repeated. Once the text has been entered, and Ayab has been launched, a message similar to this will appear, showing your last log in. To launch Ayab again, simply use the up arrow key and hit return to repeat the command  Creating an AYAB desktop shortcut for Mac that will work without opening the terminal each time
Using Finder, open Applications and find AYAB. Right-click on AYAB and select “Show Package Contents”.

Locate “AYAB” under MacOS. While holding down the command and option buttons, click and drag that icon to the desktop. This will create an ayab shortcut that does the terminal stuff for you you can change the icon by copying and pasting the icon image in “get info” but it works fine without it. These icons will appear in your dock after double clicking on the icon   The ayab window opens with only the load image option highlighted Click on the load image file to open an image, and the remaining features of the program will now be available If you quit ayab, the terminal window remains active Quitting terminal called up this window for me only the first time I did so.

DBJ: more than 2 colors per row 3

Previously published related posts:
Img2track_multiple colors per row dbj, each color knitting only once 1/21
DBJ: more than 2 colors per row 2 12/19
DBJ: more than 2 colors per row 1 12/19 
Revisiting Ayab_multiple colors per row DBJ 2 1/20
Revisiting Ayab_multiple colors per row DBJ 1 1/20

Reducing the number of rows on the front of DBJ fabrics and the associated elongation of the planned design matters so some designers far more than others, at times only in specific projects.
It may remain something in one’s wheelhouse that is not worth doing because one can.
When I was knitting garments and art-to-wear pieces I found I preferred to work in 2 color dbj, plying thin, sometimes space-dyed yarns and dropping threads, replacing them with the next shade in the chosen color wheel spaces to add more colors per row.
Long before computer interfaces that made downloads or even color separations easy, most knit artists used punchcard machines, often the Passap Duomatic, lining up long individual panels to create large, non-repetitive images, Nicki Hitz Edson among them. That said, the topic has remained   interesting to me.
In the post written on 12/19, an option was presented for having each color in each design row knit only once rather than twice. Tables in a Numbers spreadsheet were used to produce the necessary color separation.
The present goal is to repeat the separation process using other possible DIY methods.
To review: the dbj automated separations for more than 2 colors per row with the exception of the Heart of Pluto one when using the Ayab interface generally result in each color, in each design row knitting twice. This is also true of default console separations in the E6000.
The yarn for this fabric needs to be thinner, colors easily become muddied if not chosen with care, there are 6 carriage passes for each design row of knitting, and charts and downloadable repeats including all knit rows become considerably longer.
When experimenting with colors keep careful notes about your own color placement in each yarn changer location, they may not match those assigned by the download program or in the original chart.
DAK offers the option of printing templates for its DBJ separation methods.  They may be used as guides for using the designs outside the program, whether for download to electronic knitting machines or to be followed in punching cards.
Files may be opened in the DAK Graphic Studio Module with the intent to convert them to stps for use in its universe or to adapt the design for other uses outside it.
My experience with several trials of small images in 3 colors is that the resulting design conversion is faulty.  The file size morphed into a 40X40 repeat as opposed to the original 12X14, leaving no option but to draw the design from scratch in the stitch design module.  
My third attempt finally got my 3 colors represented properly, but still in the 40X40 pixel size, not worth troubleshooting, redrawing the motif is far easier and more straightforward.
Img2 track will perform the separation but does not offer a charted view or template for it. It has the added interesting function of immediately reducing the file by half because upon download the image will be lengthened automatically by a default setting to double length on the Brother machine. The issue may be addressed by doubling the file in length prior to selecting it with img2track or the stretch factor in the program may be changed to 2, also before selecting the file for separation.
I prefer to manipulate files as needed prior to opening them in any program for download, believe it makes patterning errors easier to correct, and avoids forgetting to change settings when returning to knitting the particular repeat again. In the January 2021 post, I suggested manually pushing back to B position all needles in work prior to the carriages returning to the left on every other row as one way to reduce the resulting elongation in the designs. Here the plan is to achieve it by amending the color separation and its needle selections.
One of the advantages of DIY is that the color order in the separation may easily be matched by that in the color changer.
Repeats should contain an even number of rows and may also contain rows where not all colors are in use. The first starting repeat:  The often published convention in performing dbj color separations is to begin ordering the colors based on the number of cells they occupy in the first row, here the yellow would be followed by black and then red. Other programs start with the first pixel color on the left by default.
After drawing the repeat in Stitch Designer, working with Dak choosing color separation C, and exploring print options, one may obtain a template. Its screengrab serves as a guide to tracing pixels, the results match the Gimp separation which follows.
DAK automatically mirrors the motifs horizontally prior to working with them in any way. The mirrored DAK template compared to the in-progress Gimp separation: My goal is to produce the fabric with each color in each design row knitting only once by changing the separation, the function performed automatically by Ayab’s HOP code.
This technique applies to double bed work only, is not suitable for single bed 3 colors per row slip stitch.
The backing used is bird’s eye on the ribber, with slip stitch set in both directions and using both lili buttons. The result is that every other stitch knits on the pass to the right in any color used, the alternate needles knit on the return to the left completing one full row of knitting in that single color on the purl side.
The main bed needles are preselected on the way to the left, create stitches on the way to the right, as they flatline. Since there is no needle selection, as the carriages return to the left, no main bed needles will knit, resulting in only one row in the color being carried knitting on the top bed as well. Needle preselection continues to be made for the next row to be knit after the color change.
This makes for a more balanced fabric unless colors begin being skipped for multiple rows, in which case the ribber stitches may even form small ridges and the main bed stitches will become more elongated until the skipped color is repeated.
Working using Gimp alone
It is possible to color separate using only Gimp. One of the tricks is to use significant magnification, along with the view grid and snap-to-grid options when working with developing or editing designs.
In the latest version of Gimp for Mac, using the fuzzy select tool, selecting pixel color segments allows for color substitutions when converting charts to BW prior to the final png save.
It may be achieved by clicking on a single color, followed by holding the shift key, clicking on more colored pixels for multiple selections regardless of color, and then selecting bucket fill with the replacement color. Using select by color, followed by using the bucket fill tool, changes that particular color globally throughout the repeat.
As selections are made, dotted lines outline selections until after the color change and the image has been fixed.  Colors are fixed by choosing the rectangle tool and clicking in the work window outside the image, those dotted lines will then disappear.
This separation begins with black, the first color pixel on the left.
The original image is scaled X3 in height to 11X30, the file resulting from the separation will be scaled again X2 prior to knitting the repeat after it has been completed.
Copy and paste the scaled X3 results on a larger new file so that color markers for each row may be added, horizontal guides every three rows help define each expanded, now 3-row color sequence.
Following the color rotation markings for each row, erase colors unlike it and not represented in each design row to its right, so where the black marker pixel is on the left yellow and red are erased, where the yellow marker pixel is black and red are, and where the red marker is black and yellow are. That single row with no color red is left blank.
Those extra columns on the left are cropped prior to converting the file to BW. The results on the far right would need to be used double length, whether scaled before the final file save or after download, prior to knitting. Depending on the machine and the program used for download, if the direction of the design matters, the result may need to be mirrored as well.  Developing the test png on the elongated repeat My test png, mirrored for download to the 930.
I had color changer issues with yarns being picked up 2 at a time fairly frequently, which were likely static related and improved following a rare use of yarn spray and a humidifier.
Having end needle selection, KCI on the main bed helped avoid issues with edge stitches not forming properly.
I tend to grab yarns randomly when swatching. The resulting colorways are not planned for use in finished items, they are explorations that help illuminate subsequent choices.
The yarns used in the swatch are of three different weights, so tension needed to be adjusted to accommodate the thickest yarn, resulting in more elongation of some of the stitches on the front of the fabric. The latter might be far less noticeable when knitting with thin, equal weight yarn selections. The design can be easily identified and it is also seen that colors are indeed knitting a single time for each design row. There is an exception on a single row toward the bottom of the swatch, where blue and white have knit together during tension adjustments on both beds.
One drawback to this method is that since it is downloaded as a fair isle, the capacity of the machine to offer prompts and reminders as to which color is in use and which selection should follow in knitting 3 color dbj is lost.
Testing the concept on a design where more rows have less than 3 colors represented. The repeat is slightly modified, from the one used in the second 12/19 post Here it is shown modified, with rows containing fewer than 3 colors marked. Separating the repeat using only Gimp:
the file on the right rendered double length
and in turn with the second of every pair of black pixel rows erased the comparison between the two I left the color changer set up in the same sequence and yarns used in the previous swatch, so colors do not match their placement in the charted design. I stopped knitting when the color changer carried 2 colors across a whole row, and I did not notice the error until I had reached the other side. A repair can be made easily, but I chose to stop since the repeat was previously untested. There is a dropped stitch also missed on the purl side, an easy repair when a piece is finished.
The fabric is narrow as a result of the slip settings, the cast on and beginning and ending rows of knitting need to be adjusted or they will stretch out quite a bit compared to the remaining knit.
The proof of concept with each color in each design row knitting only once: The 12/19  post also compares its repeat knit using the initial double-length file to the one resulting from the amended repeat with each row knitting only once for each color in each design row

Multiple color drop stitch lace using img2track and more

WORK IN PROGRESS

There are many fabrics where samples may be knit using the proper color separation and released just prior to binding off. Samples and designs may be found in several of my previous posts.
End release is a possibility depending on how the repeat is programmed but does not always produce good results. As can happen in any fabric, what works in swatch size may not when knitting far larger pieces. Fuzzy yarn is problematic in many knitting techniques, it is best avoided in these fabrics. No matter the yarn, after knitting longer pieces, I have found sections that simply refuse to unravel. In addition, if long stitch shapes are distributed on knit striped grounds, the release needs to happen at a minimum when the top of each shape is reached. A sample with drop-stitch interrupted by all knit rows with only one color released. 500_986The repeats for designs may be self-separated to suit.
For more than 2 colors per row the built-in separation in img2track may be used, where any number of colors are selected for each design row and repeated twice. Passap separates for 2 colors with each pixel knitting twice on every row by default, but in Japanese machines, the pattern needs to be separated and programmed using other means.
The knitting method suggested here should work with more than 2 colors per row are separated by the software.
The post on Using Layers in Gimp for color separations illustrated a method for obtaining the necessary file to match those built-in variations when working in only two colors. The repeat is one that was separated and used in a previous post Here the file is separated quickly using Layer menus in Gimp alone Three variations of the final png files are shared The last appeared the most interesting visually to me when tiled This is the appearance when a different design was entered in img2track. The separated file 3 color file in BW is not shared. The method for knitting the pattern: the long stitches are formed by loops that are created on the top bed and dropped on the following row.
This is the method I used in my early dropped stitch samples: to begin with, cast on for every other needle rib, knit 2 circular rows followed by one-row all knit rib, transfer all main bed stitches to the ribber. For an open stitch cast on directions and photos see the post.
The pitch for every other needle Set up needles on both beds for every needle rib with an extra needle in work at each end on the main bed, cancel end needle selection (KC II). With the main bed needles in the B position, set the knit carriage to slip in both directions so as not to pick up loops across the whole row on its way to the left. Change the pitch for when working on every needle on both beds.  Make the first pass toward the color changer, needles will be preselected for the first pattern row
COL: the ribber remains set to knit every needle, the main bed to slip in both directions. A piece of tape in front of needle butts of needles in A position aside the edge of needles with stitches on them on each side helps keep from accidentally moving extra needles into work when dropping whole rows of stitches
COL: change color, as carriage moves to the right, selected needles will pick up loops on the main bed that will form the long stitches when dropped, while the next row of pattern is preselected, so by the time the carriage has reached the right side of the machine, the repeated needles selection is still present
COR: using any convenient tool (I use the edge of a piece of garter bar or ribber cast on comb), bring all needles in work out to E, and use the same tool to return all stitches back to B position. The loops formed on the main bed will be released forming the long stitches: check that all needles are indeed empty and that loops are free and between the beds
As the carriage moves to the left again toward the color changer, the ribber only will knit all stitches, needles on the main bed will be preselected for the next row of long stitches, selected needles do not knit until the next carriage pass from left to right.
COR: colors are changed every 2 rows
Ayab users have a different alternative for knitting this fabric as described in the post, using the circular ribber option. Instructions are given for dropping a single color or both. I cannot imagine manually dropping stitches after every row of loop formation on the top bed for any large piece in this manner. As time passed, I developed a hack for using a second knit carriage with a modified sinker plate.  Anyone with a compatible second knit carriage may use it with the resulting modification to knit a variety of fabrics much more easily, including any that would require the ribber settings changed in both directions, more convenient if the action is required every even number of rows.
Back to drop stitch in 2 colors (or more) using img2track, changing the base design to a small geometric shape. The 8 stitch repeat scaled X 4 in length as separated in the previous post to 8 stitches by 32 rows is used in the following samples.  Rather than relying on manipulating it in width or height and programming each repeat the changes in my swatches were made using variation key selections on my 930.
This type of fabric is best knit using a yarn with no memory, that will allow for retaining the blocked shape. The elongated stitches can have a peek-through quality that will allow for solid knit in a different color, an undergarment, or even bare skin to show through.
Working with a small geometric design to start with helps to develop a sense of the change in its aspect ratio as the original is scaled and knit in different widths and lengths.
Use any separation that allows for knitting each color pixel in each design row twice.
Begin with carriages on the right / COR
After EON cast on and knitting the first full row from left to right, transfer the top bed stitches to the ribber. Place needles in work on the top bed in the B position with first and last outside those in work on the opposite bed. This will allow for edge stitches to be dropped in pattern as well. With the transition planned to every needle rib, the pitch needs to be adjusted accordingly The second carriage, C2 is set to KCII as well. It will be advancing the design with each pass as well and will drop loops on the first pass, preselect for the subsequent pattern row on the next
COR: using the paired carriages set the knit carriage to slip in both directions so as to avoid picking up loops on every needle in work on the top bed, the first row is knit on the ribber only toward the color changer.
Download the repeat.
Program it for the width of the needle bed.
Cancel end needle selection on the top bed, KCII
The separation is technically entered as a fair isle design, variation keys for altering the repeat in the individual machine brand ie double width or double height may still be used.
While moving to the left the first pattern row is preselected.
COL: When the left is reached, change color, the top bed remains set to slip in both directions, the ribber to knit in both throughout.
Before moving to the right for a single time push selected needles back to B so as not to pick up loops on the way back to the opposite side. The second pattern row is preselected during the move to the right, the ribber knits every stitch
COR: knit to left on creating loops, concurrently the next pattern row is preselected, I prefer to change color at this point leaving the carriages to the far left
C2OR: use the second knit carriage with the hacked sinker plate set for plain knitting, make 2 passes with no yarn in its yarn feeder. The first pass drops the stitches. The second pass returns it to the right leaving all needles in the B position. Because no cam buttons are selected in this version, the carriage does not engage the belt as it would if it was also used for advancing patterning.
COL: with the new color no loops are picked up on the way to the right, needles preselect for the next loop row created when moving from left to right
COR: knit back to left creating loops
C2OR: use the second carriage set for plain knitting to drop loops on as it moves to the left, needles are flatlined in B on its return to the right
It is easy to identify the last color used by looking at the ribber. At the completion of each stitch drop, with COL, ribber stitches will clearly be in the last color used.
COL: with the new color no loops are picked on the way to the right, they will be formed on the second pass returning carriages back to the left.
C2OR: use the second carriage for 2 passes
Repeat the last 2 steps until the desired length is reached
Transfer all stitches to the top bed, create a loose bind off tested on the test swatch.
The sampled repeats altered using variation keys in the 930
8X32

16X32

16X64 The transition in aspect ratio as the original repeat used on the right is changed to double its width Here the comparison is made to the double-wide repeat also doubled in length
The elongated stitches allow objects behind them to peek through Another 2 color variation  Previous posts include samples isolated on striped grounds, using 2 colors.
Adding a third color can make the overall appearance muddy and small designs can appear lost. One sample in the post Here the goal is to use the img2 track separation, maintaining the same color change rotation in each piece.
Reviewing points to consider: in more than 2 colors dbj separations, the double-length variation key is set automatically except in the 950i, where it needs to be set manually.
In knitting drop stitch, the repeat chosen must have each color present in each design row unless the shapes are deliberately altered with solid color stripes in each color. The software is smart enough to recognize any design rows in which a color is not represented.
In conventional dbj, this keeps the design continuous, but in drop stitch, those extra rows will produce an all knit stripe interrupting the overall design.
The software scales the height of the motif to half the original, due to the fact that the double-length variation key is automatically turned on, restoring the original aspect ratio, the png loaded needs to be the original repeat scaled to double its height.
In DIY a small design will likely be less recognizable than larger ones, but working with one can help one understand how stitches can be formed.
The initial design is 6 stitches by 7 rows. It was stretched in width since the fabric elongates the design, and in height because to software will, in turn, reduce that by half to 14X12. The tiled potential appearance as a dbj fabric:In the first sample three carriages are used:
after the basic cast on, transfer and set up needles as described for all variations.
To use the second knit carriage to drop stitches, the first preselection row is made from left to right with the color 1. As the pass is made to the right, no needles on the top bed pick up loops, the ribber knits in that color, preselection for the next row of knitting is made.
As the carriage returns to the left the first row of loops for the long stitches is formed, the ribber knits the second row in that same color.
With both carriages to the far left push the button selection for the next color selection. The number prompts for color changes by the machine will be off by a row during this process.
With the second knit carriage and its altered sinker plate on the right set only to knit make two passes, returning it to the far right. The first pass drops the loops, the second pass returns empty needles to the B position, creating the long stitches.
The paired carriages will knit only on the ribber as they move from the left to the right again, preselecting for the next row of loops. They will place loops in the pattern on the top bed needles as they return to the left, and knit a second row on the ribber.
With carriages to the far left push the button selection for the next color selection.
Use the knit carriage for two passes from right to left, repeating the two steps for the length of the piece.
When the top of the piece is reached, drop any loops on the top bed before knitting a row on the ribber and preparing for transferring stitches to the top bed and binding off.
Only one set of loops is created in each color.
What of end release? because all 3 colors are present in every row, the design is suitable. The first preselection row is from right to left.
I found the combined carriages harder to push, and the knitting wanting to ride up toward the ribber bed needles.
The bottom of the swatch has loops released before a transition to plain knit simply exchanging colors every 2 rows until the end of the test was reached. The top duplicates the effect achieved above by pushing preselected needles back to B position with a tool prior to moving with the new color from left to right. Side by side comparisons: If the end release fabric is preferred but the stitches riding up are a nuisance, the carriages are hard to push, not all stitches release on a larger swatch, or a slightly fuzzy yarn is used the same result is it possible once again using the modified knit carriage to drop stitches making passes from the right?
The problem with that concept: if the knit carriage or any other tool is used
periodically to drop stitches in a long piece when it moves across the row, it drops on the first pass, leaves needles in B position on the second pass when
returning to the right. As knitting resumes with both carriages, no loops are picked up on the first pass to the right, so the pattern with colors dropping for 2 consecutive rows is interrupted, resulting in a patterning error. Selectively dropping stitches while maintaining proper needle preselection is impractical.
Also, if the intent is to use the knit carriage also to select and drop stitches for 2 rows out of every 4, the motif would need to be lengthened several times. I found when programming the far longer repeat the software refused to make the proper needle selection, switching every 2 rows rather than repeating the same multiple times. That aside, the number of passes required becomes daunting.
Changing color selection and order may make the individual shapes more noticeable: Any published or self-drawn separation for 3 colors per row patterning including every color in every row of the original design may be used, programmed as a single bed design, and knit for end release.
This swatch is only 24 stitches wide, it was a start in an attempt to place a better-defined geometric shape on a striped ground, with spaces where not every color is represented in every row between repeats. Its dbj version has some interesting surface texture on the reverse It is only part of the finished piece. The same yarns and tensions as in the previous samples. Two of the problems with end release reared their heads: the color changer side formed too short floats producing a side edge a different length than the other, and several stitches were difficult to drop from the top to the bottom of the knit, with the yarn even breaking in some spots. 

Working with only 2 colors makes the process for me far more predictable and manageable.

Previously published related posts:
Revisiting drop/release stitch lace 1  11/17
Drop stitch lace using Ayab software 2/ HOP 2/20
Drop stitch lace using Ayab software 1/18
Geometric shapes in drop stitch lace 3, end release  6/15
Geometric shapes in drop stitch lace 2, Brother KM  6/15
Geometric shapes in drop stitch lace 1, Brother KM  6/15
Drop stitch lace, 2 colors per row, Passap KM 10/13
Drop stitch lace, 2 colors per row, Japanese machines  10/13
Revisiting knit “bubbles” brother KM 10/17
A bubbles cousin 9/13
More knit bubbles  9/13
Knit bubbles and “stitch ditchers/dumpers”  9/12
Working out the kinks in my drop stitch lace saga  9/12

Using Layers in Gimp for color separations

2023 The layers menu in Gimp 2.10.34 no longer offers the difference mode.
From the manual: “If you need to stay compatible with older GIMP versions or you need to use the legacy layer modes for other reasons, look for the icon to the right of the layer modes selection.
This drop-down menu will let you choose between Default and Legacy. If you choose the latter, the layer modes list will only show the legacy layer modes and all modes will have “(legacy)” behind their name (the selected mode will use the short version (l). ”
To make the dialog available: click on Legacy to switch mode selections.  In December 2022 I began to experiment with layer transparency please see the post Gimp Update for Mac 3.  Over the years I have developed personal methods for creating color separations for many types of knit fabrics, born from lots of experimentation when published resources were absent or extremely limited.
I continued to share methods as they evolved from increasing familiarity with specific programs or as I was introduced to new ones.
Since I began to use paint programs including Gimp I had very limited experience using layers and did not consider how they might be used in color separations for BW knit repeats.
In my last post on fantasy fair isle ribber fabrics, Claudia Scarpa shared her layers method and subsequently published a Youtube video for obtaining a separation for a very similar fabric to the one I developed beginning with a large design motif that in her instance was also placed specifically on a larger ground.
Her method for separations in 2 color work sparked my interest in using the steps to yield knitting patterns for varied textures and stitch types, beginning with dbj.
Using
will display layer options in my Mac on the bottom right side of the screen A simple geometric shape is scaled in Gimp to twice its height, check that Quality Interpolation is set to None. I have sometimes had issues with scaling in Gimp, particularly when working with small repeats. The cause appears to have been that the Quality, Interpolation, needs to be set to None and may randomly change while working through several steps in processing any image or after a program restart. Arahpaint scaling is still an excellent option for knitters who have it available.
the white ground of the resulting image is rendered transparent by using Color to Alpha and will constitute the first layer for the separation process Select New Layer from the Layers menu (see chart), choosing the background or foreground color to have a white screen. It will share properties with the alpha repeat such as pixel count, magnification, and the grid view if used.
Use the pencil tool to draw a repeat that will be used to fill the new layer, followed by using the rectangle tool to select what will become the pattern used to bucket fill the whole layer.
The latter may be the smallest possible selection or even that of complete rows as in my chart. Copy the selection, and it will be saved to the clipboard and remain available for filling with the pattern unless the program is quit. It may also be saved as a pattern for future use.
After using the rectangle select tool, remember to click in the window outside the image to set the layer before using the bucket fill tool in the pattern fill setting, or the whole layer will simply fill in with a single color. In the layers dialogue, use the mouse to drag and drop the alpha image icon for the triangle layer onto the newly created one. The selected icon will appear surrounded by a border when chosen, a new icon will appear during the step.  Both layers measure the same pixel dimensions, no placement adjustments are necessary. The mode, highlighted here is changed in a later step.  Color invert the new image  Click on the downward pointer to the right of Normal and select Difference. The result is a repeat that may then be saved and used doubled in height to knit DBJ in a variety of settings.
Elongation after download can be avoided by working with the same initial image scaled in height X4 and following the same process, saving and using the repeat on the far right. The same separation was achieved using other methods in the post on fantasy fair isle.
Possible DBJ settings on Brother machines using the elongated final repeat are shown in this grab, part of the postEOR refers to a repeat that would require double length after the download, the same machine settings apply to any image created in a double-length format prior to download. Are punchcard knitters left out? In the post on the color separation used for the KRC equivalent separation for a punchcard two results were presented, the full card and the starting design shown with the color reversed repeat of the above. The process begins with obtaining the double-length separation after saving the last file on the right as PNG discard any files still open. Open the saved png and process it the same way, changing the ground Save the last file as png. Punchcard knitters would need to tile the fileX4 in width and height X2 but the final repeat appears different than that in the punchcard post, the proof of success or failure is in the knitting. If the swatch is knit on electronic models, the first preselection row is made from left to right, as it would be if using the built-in color separation. The main bed for this fabric after the preselection row is set to slip in both directions, the ribber, using an even number of needles, is also set to slip in both directions with lili buttons. The 8X32 png The result from repeating it twice indicates the separation indeed works. When a color separation is downloaded it is used as one would a fair isle. If the motif is representational and direction on the knit side matters, any repeats may have to be mirrored horizontally if they are automatically reversed by either your software prior to download or your machine model after it.

There has been renewed interest in the MK FB group on drop stitch lace recently. I plan to address using this repeat in a future post on knitting the fabric using img2track. The 16X72 double-length PNG A quicker matching result:
begin with the motif lengthened X4
open a new layer, bucket fill a striped ground and use transparency to change the white in the result to alpha. The layers are immediately combined into a new image
color invert the resulting file
change layer mode by selecting difference from the menu, save the resulting PNG
Tiling to visualize alternative repeats, beginning with the 24X72 pixel fileThe file for the image in the center, modified to 24X144 pixels file for the image on the right, modified to 48X144 pixels  Removing the color on every other row for use in specialty fabrics ie drop stitch lace using a modified stitch dropping tool with a now edited 24 stitch repeat, suitable for punchcard models:  The image is processed as for the previous separation, the final png is exported. Open the saved in Gimp.
From the Layer menu choose new.
Create a pattern for bucket-fill in pattern using color, in this case, blue.
A new image immediately appears, export it as a PNG.
Open the saved 3-color PNG.
In the tools menu choose the second option for fuzzy select by color, the icon will change. Using the rectangle tool, select a single blue row, after the selection, press and hold down the shift key and repeat selections of multiple rows in the same color. Each selection will be bordered by a dotted line. Release the shift key. Click on the rectangle select tool and then again in the work window outside the image to set it. The dotted lines will disappear. The same action is repeated if working on segments of the full file at a time.
Export the fully altered file as PNG ready for download, or print a gridded version to follow in punching a card. The 24X72 new png MOSAICS: For proof of concept, I intend to use separations for fabrics accompanied by knit samples in previous posts,  beginning with a mosaic one, achieved in the post. The images shown are for the final repeat as separated there are shown at the top of this new image. Below comparisons are made between the original download file and its companion elongated repeat alongside the same developed using LayersBoth results require scaling X2 before knitting, whether by button setting changes in the repeat after download or in Gimp before.  After reaching the step where the layer mode is changed to Difference (or Exclusion), stop and save the png, using color reverse at this point will revert to previous a previous layers view open the saved png in Gimp, use color reverse, then scale the result doubling its height, save the png for download and knitting without changes in any machine settings. Testing another image separated in a previous post: the original charted image is now rendered in black and white the repeat as a PNG  tile check The process in LayersThe very last file on the right is saved as a PNG. In turn, it is opened again in Gimp, scaled to twice its height The non-elongated repeat matches that in the punchcard, which was knit with the machine set to double length Exclusion is the alternative Layer mode which when following the same process yields identical results. A block slip stitch design from the post requires color inversion and doubling the length. A: design motif
B: lengthen X 4
C: color reverse
D: new layer filled with pattern
E: color to alpha immediately results in F
F: save the PNG for download

Gimp update for Mac 2

The latest Gimp update
2023: Threshold in version 2.10.34 is now disabled by default. To activate it or to add other tools ie curves to the tool menu, go to Gimp, Settings, and select Toolbox.
In the Tools Configuration Window,  active tools have a common icon to their left, new ones may be selected and added, I chose Threshold and Curves. After clicking  OK, a restart is not necessary, the new tools will appear immediately for use in the toolbox.  The curves tool enables editing for changing the color, brightness, contrast, or transparency of the active layer or a selection. While the Levels tool allows one to work on Shadows and Highlights, the Curves tool allows one to work in any range. It works on RGB images.
2022:The program now allows for setting pencil pixel sizes to odd and even numbers accurately, eliminating the need to save brushes for sizes missing in previous versions See color exchange notes using the new Fuzzy select tool as opposed to using Color Exchange
Notes in post Numbers and GIMP: online punchcard patterns to electronics 2 contain information on printing punchcard designs to scale for tracing and marking cards prior to punching holes.  2021: Prior to attempting color separations of any sort, it is useful to have some understanding of how black and white pixels or punched holes relate to knit/ tuck/ slip setting stitch formation and their effect in both single and double bed techniques.
A recent post explored the use of layers for color separations in Gimp. It is a reliable, quick way to execute them, especially on large images. As is often found, the same results may be reached in a variety of ways.
Coupling the use of the shift key with rectangle selection and working in high magnification offers additional options in Gimp.
While working on any gridded and magnified design motif use the rectangle tool to select the rows that will be altered, make the first selection, and after doing so press and hold the shift key, continue to select specific areas, and then choose color invert in this first instance and the action will be applied to all selected areas. If working on parts of the image at a time repeat the steps until the whole image has been processed. Release the shift key when done. The image is set by clicking anywhere in the window outside of it.
In the past, I have used red pixels in an extra column beside the repeat to mark rows that need to be altered. The column is cropped prior to saving the final png for download to the km. The step is not a necessary one.
This is an illustration from another post, where color inversion was planned in the repeat selections, each of which is surrounded by dotted lines that will disappear after they are set. The red cells will change color as well after inversion, making it easier to track the placement of completed choices A result from using the method on a large image may be found in the post on fantasy fair-isle.
In the above, they are on what may be thought of as even-numbered rows of the design. If the plan is to use Cut to eliminate those same rows, the red cells need to be shifted down to “odd-numbered” rows. From a repeat in development for a drop stitch lace design Working through the process with an easily recognized small shape, the often-used small triangle.  Scaling in Gimp can become erratic while working on several files.  Check that the interpolation is set to none if there appear to be odd scaling issues in the new image. When scaling in one direction only is intended, the chain link must be broken. At each step save the resulting png to make it available for further use ie additional scaling in height and width.  The results with the selection of even rows simply shift the result up a row Test in your version of the program to see whether releasing the shift key prior to making edits changes them. Either way, being consistent in the choice makes for less confusing results. Experimentation takes a matter of seconds.
Depending on your need the saved PNG may also be color reversed or scaled to double-length
using the rectangle tool, either odd or even rows may be chosen, remaining consistent for the height of the repeat in a scale to suit the end fabric goal. Here the original file is lengthened X2
working with the original file lengthened x4. The selections can happen on every row or every other, whether singly or in pairs. Note the difference between making the first selection on the first pair of rows or the second. 2021: Gimp update for Mac
Supported OS: macOS 10.9 Mavericks or over, to run 2.10.24 in my new iMac, M1, OS12, needed the installation of Rosetta. Rosetta 2 is an emulator designed to bridge the transition between Intel and Apple processors. In short, it translates apps built for Intel so they will run on Apple Silicon, more info 

The previous post on this topic: 2019/10/07/gimp-update-for-mac/
I have been spending more time exploring version 10.22 and am becoming more familiar with new features and design options. There are slight variations in behaviors depending on the Mac OS version. Windows updates happen more frequently. GIMP 2.10.24 for Mac OS is now available.
Gimp has a wide range of paint tools The most commonly used in creating repeats for knit designs are Pencil, Paintbrush, and Bucket Fill.
The Pencil tool is used to draw freehand lines with a hard edge. The main difference between it and the Paintbrush is that although both use the same type of brush, the pencil tool will not produce fuzzy edges.

Present experiments are placed in alphabetical order. Topics:
Brushes and patterns
Canvas resize, offset 

Colors exchange
Colors threshold see grid options
Grid options, Guides, Color separations
Symmetry Painting

BRUSHES AND PATTERNS
There are many very good videos on using multiple versions of GIMP on Youtube. Most focus on working with very large images in huge numbers of colors, and brushes or patterns in the tutorials are often larger than the maximum stitch count on our home knitting machines capable of electronic download and with needle counts of 180-200. In addition, punchcard machines have a 24-pixel width repeat constraint. The content of such published material and tutorials can be overwhelming, but isolated techniques for the required binary bit-mapped knit scale are easy to sort out.

Many knitters designing small repeats use very simple programs and enter pixels singly or copy and paste in small groups. Some simple, quick functions in Gimp can simplify and speed up progress considerably. Punchcard knitters may use the same techniques to set up their 24 x X custom length repeats and tile the results to visualize how they line up when knitted in multiples.
Some content paraphrased from the online Gimp manual: in GIMP, a pattern is a small image used to fill areas by placing copies side by side. You can use them with the bucket fill tool. They vary in size and are used for filling regions by tiling, that is, by placing copies of the pattern side by side like ceramic tiles. A pattern is said to be tileable if copies of it can be adjoined left-edge-to-right-edge and top-edge-to-bottom-edge without creating obvious seams, such patterns are used in standard knitting repeats. The same effect may be obtained by using the Filter, Map, Tile option on the drawn image.
With the bucket fill tool, you can choose to fill a region with a pattern instead of a solid color. To make a pattern available, place it in one of the folders in GIMP’s pattern search path which includes two folders, the system patterns folder, which you should not use or alter, and the patterns folder inside your personal GIMP directory. The .gbr (“gimp brush”) format is used for ordinary and color brushes. 
Photoshop ABR brushes are also easily imported for use.
Pressing the refresh button causes GIMP to rescan the folders in your pattern search path, adding any newly discovered patterns to the list. This button is useful if you add new patterns to a folder, and want to make them available without having to restart GIMP.
GIMP includes a set of 10 “paint tools”, which, except for the ink tool, use the same set of brushes. The brush pixmaps represent the marks that are made by single “touches” of the brush, which is desirable in working with knit scale bitmaps. Brushes can be selected by clicking on an icon in the brushes dialogue, the current brush is then shown in the Brush/Pattern/Gradient area of the Toolbox. Clicking on the brush symbol there is another way of activating the Brushes dialog.

When you use the Copy or Cut command on an image or a selection of it, a copy appears as a new brush in the upper left corner of the “Brushes” dialog. This brush will persist until you use the Copy command again. It disappears when you close GIMP.
Building a personal brush pattern library on Mac: open software preferences locate folders on the bottom left and click on the plus sign aside folders icon at the bottom left, it will change to a minus sign, and folders become visible select brushes, two options will appear. If a proper choice is made for the addition of pattern files, a green button will appear single click on the filing cabinet icon on the right,  a familiar Mac finder window will appear double click on the patterns folder, and its own window will appear,  right-click in the window below the last entry, a smaller window appears, choose the add new folder option. It will appear as “untitled”  and will be added to the existing folders, rename it “my brushes” or any other choice, and the new folder will be added within the brushes one Its place in the brushes list will be determined by its initial letter, the contents are in alphabetical order. For future use, any saved brush may be dragged and dropped into the named personal pattern folder icon, or into the folder after it has been expanded or opened in its own window. My opened brush folder After brushes are added, the refresh button below the brush dockable dialogue may bring them up without having to restart the program. After saving these 3 images as .gbr files and placing them in the appropriate folder they appear as available for use  To install .abr files on Mac:

create a new Photoshop folder within the Gimp Brushes one
Download the chosen files, drag and drop the images or folder from the downloads folder into the chosen Gimp one, they will be available after a Gimp restart
The free files I tested were very large in size, did not scale down to use for knitting cleanly, and even though they appeared to be BW they opened as RGBs making the conversion to BW indexed quite dithered. They are composed of assorted leaves and snowflakes. When exporting self-drawn brushes, the option is offered for adding spacing surrounding the shape, here a 10% addition was chosen Patterns may be saved in a similar way. Since GIMP 2.2 you can use .png, .jpg, .bmp, .gif, or .tiff files as patterns.
Saving patterns from large to tiny may be achieved using the same method as in saving brushes. To save personal patterns, instead of choosing the file cabinet icon in preferences, one may choose the folder icon, following a similar series of steps to those above, including verifying the contents of the newly created folder Use Windows, Dockable Dialogues, choose Pattern. The patterns will show on the right of the Gimp window and are viewable once you click on the fill window below the tools on the left as well.

Open the image to be filled
Click on the paint bucket tool, and select the Pattern fill type. Click on the paint bucket, then on the pattern you wish to use on right, hover over the canvas with the paint tool, click on it and the image will fill in the chosen pattern.
Or click on the pattern icon, scroll through to the desired pattern, click on it, then on the paint bucket tool, hover over the canvas with the paint tool, and click on it to fill.  The + or _ option scales the size of the pattern view, it is handy when tiny or very large repeats are chosen. The canvas for the pattern fill needs to be large enough to accommodate the pattern in repeat.
If the fill fails, check to see that the bucket fill mode was not somehow changed from normal to one of the many other options Here the skull is used to fill a 400X400 canvas, an even multiple of its size If the canvas is not in a full multiple of the whole pattern, part of the repeat is cropped  Using the same rose image tiled using the Filter, Map, Tile menu produces similar results when full multiples of the image pixels are not chosen, ie. here the tiling is on an 80-pixel wide canvas as opposed to a full multiple of 25 ie 100  Designing tiny repeats:
Begin with the image in black-and-white indexed mode. 
To draw my repeats, I used 1800X magnification, with grid view, exported the files as png, and dragged them into my own Gimp patterns folder.
If the goal is full punchcard repeat illustrations, then by default the width of the image to be filled needs to be 24 pixels wide, and a minimum of 36 rows high. If working as a tuck stitch, punched squares are black pixels, and unpunched squares the white, creating the tucked loops. Using the bucket tool to fill the image is accomplished with a simple, very quick stroke  The rectangle tool may be used to isolate a segment of the first repeat and the area may then be filled with a different pattern. Brushes may be resized as needed, and pasted on the previously filled image, and guides are helpful in their placement.  added info on pattern fill in Gimp 4, pattern fill, dithered portraits, and more
Canvas resize, offset:
 working with a 20X20 black and white pixel star  
Extra grid rows or columns may be added in a variety of ways to an existing motif including using these menu options These images illustrate only some of the possibilities. The chain link is used broken with the exception of when placing the star centered onto the new canvas or when moving it for manual placement onto it. Use Layers choices: resize all visible layers, fill with white. With the new canvas width equal to that of the image, the 10 desired new rows may be added to either the top or the bottom of the file respectively by entering that number in the space for the offset X or Y values, and the resulting new files are shown gridded on the bottom right.  When choosing the center offset with the chain link intact, the X and Y values will be changed from 0 to 10 in this case by the program based on the new canvas size. To add cells only on the left, the chain link is broken again, and the X offset value is set accordingly. Adding 10 cells to the right, 0 offset selection  It is possible to guide the placement of the motif onto the new canvas in any position. There will not be any visible grid as a guide, so a bit of math planning ahead for the new canvas size will fine-tune the possible placement. Again, the chain link is broken. Choose the center option but before selecting resize, click on the image, drag it to its new location, then select resize. The grid can then in turn be made visible.
Any of these steps may be undone, adjusted, and repeated as needed.  Grids and Guides: my view was magnified X 2800, and the canvas measured 24 X 36 pixels.
Magnification may be set using the pull-down below the image window, where any number listed may be chosen or typed in and set by hitting the return key, or by choosing the zoom tool. Click only on the image, and the zoom is applied to the whole image. If the pointer is used, click and drag the mouse pointer to create a zoom rectangle. The biggest dimension of the rectangle will correspond to the size of the image window. You can get to the Zoom Tool from the Image menu through Tools, Zoom, or by clicking the magnifying glass in the toolbox Anyone needing an adjustable grid superimposed on an existing image may use the Configure Grid command to set the properties of the grid and display it over the image while working on it.
One can choose the color of the gridlines, and the spacing and offsets from the origin of the image, independently for the horizontal and vertical grid lines. The configure grid dialogue:  The five different grid styles: Intersections, dots: the least visible, a simple dot at each intersection of the grid lines.  Intersections, crosshairs: a plus-shaped crosshair at each intersection of the grid lines  Dashed: dashed lines in the foreground color of the gridDouble dashed: dashed lines, where the foreground and background colors of the grid alternate, look the same as above when the image is in BW indexed mode. It is also hard to discern the separate colors in RGB mode because the dashes are so small and so close together,  Solid: shows solid grid lines in the foreground color of the grid Foreground and Background colors: in RGB Mode, click on the foreground color to select a new color for the grid, click OK Spacing: for use illustrations see GRIDS: OPTIONS
Width and height: select the cell size of the grid and the unit of measurement
Offset: moves the origin of the first cell, by the fault the grid begins at the coordinate origin, 0,0
The Snap to Grid command enables and disables Snap to Grid. When snap to grid is enabled, and a selection is moved or placed, the grid points pull on it when it approaches making accurate placement easier. If the magnification is high enough, the placement of your pencil or brush will be outlined in a dotted line. Here the snap to the area for a 3-pixel pencil is shown highlighting its possible placement location. This command is found in the image menubar through View, Snap to Grid.
The question has been asked in forums again as to how to place knit designs other than on a square grid. If retaining the aspect ratio matters, any image used for download can be scaled in height or width after it is drawn, or even after download depending on the software used.
If the intent is to illustrate the design on a knit-stitch rectangular grid, one may choose to configure the grid for any single image, or for permanent use.
For a permanent change, the default size may be set by changing user preferences, as seen here for a 1X1 pixel grid. 
To change results on any single work file use Image, and Configure Grid values to the desired ones.  Configuration options for line styles include solid, as shown above.
GUIDES
to configure guides, you can go to Image>Guides>New Guide by Percent, or simply click on one of the rulers in the image window and pull out a guide while holding the mouse Left Button pressed. The guide is then displayed as a blue, dashed line, which follows the pointer. As soon as you create a guide, the “Move” tool is activated and the mouse pointer changes to the Move icon. Releasing the mouse will place it.  As soon as a guide is created, the “Move” tool is activated and the mouse pointer changes to the Move icon. 

You can create as many guides as you like, positioned wherever you like. If the grid is set to a 1X1 square pixel default with a line border, at any point the Image, Configure, Grid option may be used to change the ground view  To move a guide, activate the Move tool in the Toolbox, then click on the guide (it will turn red), and drag it to a new location. Click and drag the intersection of two guides to move them together. Create as many guides as needed, positioned appropriately for the design. To delete a guide, simply drag it outside the image. 
Holding down the Shift key moves everything but a guide, using the guides as an effective alignment aid.
As with the grid, you can cause the pointer to snap to nearby guides, by toggling View, Snap to Guides in the image menu. If you have a number of guides and they are making it difficult for you to judge the image properly, you can hide them by toggling View Show Guides.
You can remove all the guides using the Image, Guides, and Remove all Guides command.

Working on punchcard repeats whether in designing for cards or creating a BMP or PNG for electronic download using a published repeat, guides may be set to outline 6X6 blocks as seen in factory-issued Brother punchcards, or to create custom templates.  For example, lace designs have few pixels. Horizontal guides may be added or moved at intervals between repeat segments, making certain the two knit rows are left blank as one continues entering the proper pixels. The vertical guides help in orienting and locating the pixels in design blocks to match the source.  With guides in place, pattern fill may be used, adding shapes using the tools, or brushes to place motifs. A sample of a knit repeat using the rectangle tool and the paint bucket tool combination to create filled rectangles placed in relationship to guides, creating a tuck pattern with interspersed plain knit rectangular shapes Built-in or custom brushes may be superimposed on a bucket-filled ground. Create an image in the desired width and height, here 24 X 24, and magnify at least X 800 for a grid view.
Fill with a pattern.
Place the chosen brush on the patterned ground, adjust the size and placement of the brush until satisfied, and save the image.
Consider the end-use for the pattern. For example, the designs below left would be suitable for tuck stitch, the same designs would need to be color reversed if the plan is to use them to knit thread lace. Both the original and the new image should be set to BW-indexed mode. Developing a brick version of the repeat is easy and quick. With the original image open, create a new image with the same width but twice its height, 24X48.
Set the magnification for both images to the same number, adjusting the number of both if needed so the longer canvas is in full view.
Configure the grid as preferred on the new image, and make it visible. Snap to grid is useful, but may not be necessary when working on such a scale.
Copy the full starting image and paste it onto the bottom of the new one.
Guides may be put in place to adjust for the pattern shift in the top half of the new image. A single, center guide, in this case, was sufficient.
If the full image copy is still available, align and paste it again, its left side to the right of the center guide, and anchor it.
Paste its right side to the left of the center guide and anchor that in place also. Undo and repeat steps if needed.
Check the alignment of the full repeat by map tiling, if satisfied, export it as PNG or BMP for future download.  COLOR EXCHANGE  2022 Gimp update offers a selective way to exchange colors using the fuzzy-select or select-by-color tool. The bucket-fill color works differently in some ways from previous Gimp versions.   Fuzzy-select will change any contained segment of an image in RGB Mode.  Make the selection of the area to be changed, it will become surrounded by a dotted line. Choose bucket fill, change the foreground color to the new one, and click on the outlined area, to the new color. Click on the rectangle tool and then anywhere in the work window to set the image and save it.  Multiple color exchanges in the same image.  Edit, and undo can be used to trace steps backward at any point.
Using select by color will select all areas containing that color, making global edits,   the process may be repeated within bordered segments, retaining their outlines.2023 version 2.10.34 use the shift key to fill by color, and the simple bucket fill tool once more to fill in any single, outlined areas
To change color in a solid background, as an alternative to using bucket fill, simply click on the associated icon, drag the desired foreground shade onto the ground, and release the mouse COLORS EXCHANGE older version
Color exchanges to test designs in different colorways may be made easily and quickly using the program. To test the concept begin with a simple repeat already tested for tiling originally saved in indexed black and white colors 

This icon shows the default foreground and background colors  Black is the foreground color, and white is the background.
Using such small images I often work with 800X magnification. Open the image, choose sizing, scaling, or magnification if necessary, convert to RGB mode then from the Colors menu choose Map, Color Exchange. The color exchange window will appear. Here the white “from color” is left undisturbed. Select the dropper next to the “to color”, then click on the image on the color you wish to change, a palette window will appear. Make your choice, the color exchange window will now have substituted the chosen color for black, click OK, and white design areas are now changed to the chosen blue globally. The process may then be repeated with the second color if desired.  The color exchange window will show white as the default “from color”. Click on the white bar, choose black from the palette window or use the dropper to select black from the image. The from color will then appear as black. Repeat selection with the dropper from the right of the “to color” bar on any black pixels in the image, choose the color from the palette window to replace it, and the color exchange window will display the new “to color”. Click OK, and job done. The process may be repeated multiple times on the same design or used on large-scale ones, giving one some idea as to whether or not to really commit to the estimated colors. I recently had reason to review old PC files from my Passap knitting days and came across several cut files that when converted to png format appeared in colors rather than black and white, leading me to experiment with color exchange again.  The image for the first experiment is part of a crib blanket by Cheryl GilesThe process: do not alter the original image ie. by resizing, which seems to change the color mapping responses
load the image in RGB mode
working with the foreground color, click once on the white, use the color picker to choose a color, in this case, orange, a palette window will appear, click OK, and the background color will change accordingly,  double click on the now orange background to call up its palette window, keep that window open, go to colors filter, map, color exchange
double click on the from color, the white, in the exchange window
match its values to the saved palette window working from the top down, you may find some of the remaining numbers self-correct
in the original image orange, is now exchanged for black continue, repeating the process with the alternate color, in this case, yellow. At that point, the in-process image will appear as solid black. Click on the black in the exchange window to color twice, choose white from the palette selection, click OK, and the conversion is complete. It is possible to colorize images originally drawn in black and white. The color exchange options will remain fixed throughout the process. The image may be worked on continuously and exported when color exchanges are completed, or saved and imported again after each step. The color exchange here happens consistently on the chosen background color, changing that quickly becomes familiar and easy. There are times that the repeat being processed will turn black onscreen, trust in the process and continue.
The default color exchange window using color options in the default palette. The steps for changing the background to red: the image will turn black as you work, click on the TO color selection to pick a color from the default palette to replace the white, in this case, the red, you can click OK, but do not close this last window if you want to continue, the color change will be lost Changing the black to white in summary Export the image. The transitions: Developing custom palettes in order to visualize different colorways while using the same repeat:
load the image,  right-click on the paintbrush icon, and choose palette editor, this window will open with selections for possible palette choices click on your choice, then click on the palette icon, and your color choices will appear, click on the white, to create a new background color. It will change it to the chosen value in this window when you click on that. The new color choices appear in the palette in the future unless a choice is made using resetting it to the original. Two selections may be made for new colors at the same time, but the map, color exchange option will continue to work on the background color only. These were my choices for added colors. Continuing to work with color changes, changing the white in the BW repeat to blue the black to orange My success with series of other images in using color exchange has been spotty. Online forums reveal this is a recurrent issue with no clear solutions. Suggestions include stipulating that the cause may be the version of Mac OS in use. Color reductions using ArahPaint achieve consistent results easily and quickly. There are advantages to hybrid conversions.
COLORS THRESHOLD: see GRIDS OPTIONS
GRIDS: OPTIONS
Punchcard users may use this method to visualize which holes to punch, though this particular repeat would need to be reduced in stitch count in order to be usable. Similar charts may be adapted and used for other textile techniques such as cross-stitch or even filet crochet.

Grids help with the precise placement of pixels when designing using pixels to represent stitches and rows. The grid is not visible until it is activated via the View, Show Grid option in the Image menu. To create a custom grid, the Image, Configure Grid from the Image menu brings up a dialogue that allows you to do so. Snap to Grid causes the pointer to “warp” perfectly to any grid line located within a certain distance. In most instances, when drawing repeats a 1X1 pixel grid works well on a canvas magnified enough for it to be visible when filling in cells, I recommend a starting magnification of X800.
Anyone needing an adjustable grid superimposed on an existing colored image may now adjust the grid size to suit while viewing the resulting changes. The beginning image and grid size both need to be large enough for the grid to be visible. Use the show grid, and Configure Grid commands  The intact chain link fixes the width and height aspect ratio of grid cells Considering the possible smallest repeat, breaking the chain link, and changing values progressively while viewing the results brings one closer to matching units  The image itself may be scaled concurrently to tweak grid border alignments. The final grid size below is 18X18,  the image size is shown after scaling from a width of 277 pixels (with a broken link at that time) to a final 270 pixels in width The screengrab of the above center, with a superimposed new grid; note the image, in this case, was also offset for better placement, a 3-pixel pencil was used to isolate the border of the possible smallest repeat Using Filter, Map, Tile to check alignments  The repeat reduced to 12 stitches, suitable for punchcard, and tiled to check alignments. Translating the colored image to BW indexed may take several steps and some clean-up if only Gimp is used to process it. With the colored large-scale isolated repeat, the image is opened in Gimp. The Threshold tool transforms the current layer or the selection into a black-and-white image, where white pixels represent the pixels of the image whose Value is in the threshold range, and black pixels represent pixels with Value out of the threshold range. It may be activated from the pull-down colors menu or from the toolbox.   The color image will temporarily disappear, adjust levels. Scaling to repeat size: check the image size, making certain the present dimensions match a multiple of the final repeat count for stitches and rows. If adjustments are required, breaking the chain link allows for each count to be adjusted independently from the other. In the final scaling, use the closed chain link, adjust numbers, magnify the repeat, checking it with a superimposed grid for any missing or out-of-place cells. Check the alignment, then save the single repeat, which in this case is 14X14, ready for download Color separations: there are occasions where very small repeats need to be scaled in height only for color separations. I have found such scaling to be inaccurate using the option, such as here, both of the small, single repeat, and in scaling its tiled version. The triangle motif was used in many of my early posts on color separations for DBJ and its backing options.  On a long enough canvas, the grid may be adjusted to 1 pixel by four in height. With that number of cells filled in with black in this case, if the 1X4 unit is captured with the rectangle tool, it will appear in the brush menu and will be available for use with the pencil tool for drawing with single strokes until one quits the program unless the unit is saved for future use as described via preferences  Using RGB mode, the two-color redrawn image is redrawn, A. The grid may be adjusted to 1X 1 again, B. Using magnification, I often use X1800, and pairs of rows may be selected for either color invert or value invert color options. The first will add a third color, seen in the chart bottom, the second will yield a 2 color image, seen in the chart top, B.  I have had no success with using keyboard commands for the action using my OS, find it easier visually to deal with the three colors than with the 2, especially in longer repeats. C: the extra color pixels in the rows with black pixels are filled with white. D: the third color pixel rows are filled with black. D the final repeat may be color indexed to BW and saved for download.  The appearance of the final repeat when color is reversed Another comparison of the 2 options for altering every other pair of rows in the specific color separation for a mosaic repeat. There is less filling in of cells with a different color, but in large files especially, I feel the result would become far more visually confusing to track. For more details on the specific mosaic, see  2021/01/27/mosaics-and-mazes-charting-meet-numbers-gimp-3/

SYMMETRY PAINTING
Information summary from the online manual on working with symmetry:
you can access this dialog from the image Menu bar through Windows-Dockable- Dialogs-Symmetry Painting, its icon appears below at the top right A drop-down list offers four options. As soon as you check a type of symmetry, axes appear as dotted green lines in the image window and you can start painting with the brush you have chosen.
The default position for the symmetry axis is the middle of the image window. You can place the axis where you want using the Horizontal axis position and Vertical axis position.
Disable brush transform: when you transform the drawing, the brush itself will end up transformed as well. For instance, in a mirror transform, not only will your drawing on the right of the canvas be mirrored on the left, but the brush itself is obviously “flipped” on the left. If for some reason, you want the drawn lines to be mirrored (or other transformation) but not the brush outline itself, you can check this box.
“Tiling” is a translational symmetry, which can be finite (with a maximum of strokes) or infinite. In the latter case, it is the perfect tool to create patterns or seamless tiles, at painting time. This mode covers the image with strokes.
Interval X Interval Y: these are the intervals on the X and Y axis, in pixels, between stroke centers.
Shift: this is the shift between lines on the X-axis, in pixels.
Max strokes X, Max strokes Y: these are the maximal number of brush strokes on the X and Y-axis. The default is 0, which means no limit, according to the image size.
Using a large image, and testing a few iterations helps one understand the process. The pepper brush is provided in the program and is used in the tutorial on the Gimp site. Most such tutorials are intended for working on far larger and higher resolution images, while knitting is binary and at the opposite end of the spectrum in scale and required image size. The original brush is 220 pixels in size, and the maximum number of needles per pixel on standard machines programmable at one time is 200. For exploration, any of the built-in brushes may be used, I began by scaling the pepper to 50 pixels, then moved on to a self-drawn, equal size flower motif. When choosing canvas file size, consider a multiple of the brush size. Drawing repeats uses the pencil tool.   Working with potential knit repeats the scale is reduced further. Magnification is useful for the evaluation of repeats. The smallest repeat segments for use on electronic machines may be isolated. The filter, map, and tile option easily verify how the repeats line up overall. Cropping a 24-stitch width and tiling that also visualizes the suitability of the repeat for use on punchcards with the 24-stitch limitation.  Grid view helps identify any need for “clean up”.
This rose is 24 stitches wide by 25 rows in height Open the chosen file in Gimp. Create a new file in a canvas size considering a multiple of the original.
When the Copy or Cut command is used on an image or a selection of it, a copy appears as a new brush in the upper left corner of the “Brushes” dialog. This brush will persist until you use the Copy command again. It disappears when GIMP is closed.
With the single repeat opened in Gimp, magnified several times, click on the image and use the copy command. The image will appear in the symmetry dialogue. The position may vary depending on whether the program has been closed and relaunched between episodes of testing the process. Create a new file, large enough to accommodate a multiple of the original number of pixels, add pixels for spacing between or above and below designs, set the magnification to the same number as that of the clipboard image, left-click on the brush icon, choose the image saved in the clipboard and a type of symmetry and accompanying settings, click on pencil tool, the motif will appear as on the above right, paste the image on the new canvas, undo and repeat setting adjustments until satisfied with the distribution of motifs.
Some ways of varying repeat positions working with motifs in networks were illustrated in the post To develop a brick repeat I began with a canvas twice that of the original rose, 48X50 pixels, isolated the smallest repeat, used the filter map tile option to test its all over alignment The 24X50 repeat: To decrease crowding, using the original image, the new canvas is now 40X60, with the shift decreased from 12 to 8 pixels. The result did not tile properly when mapped, using magnification 800X with a viewed grid the final repeat, 29X60 was isolated Being more deliberate with the math leads to a full, successful repeat 

Working on the gridded image, drawing straight lines to isolate color change areas in chosen colors followed by flood filling, one may begin to visualize changing the ground color behind the motif repeats Using that small triangular 8X8 repeat open in Gimp, or draw any small shape if designed by hand, remove the grid. Before using it as a brush, reduce mode to 2 colors, magnify X800. Open a new file. I found the latter needed to be increasingly small as well for the repeats to be placed accurately. After tiling using symmetry, filter, map, tile from the filter menu to check for multiple repeat alignment.   Again, preemptive math will yield images that avoid further processing. It is up to the user to recognize any problems,  the repeat here needs to and can be isolated correctly from the file on the left, it is actually only 16 rows high. Here the adjusted repeat is created on a 24X16 canvas with the same symmetry settings, and filter/mapped/tiled There may be multiple ways to achieve the same result with each motif. Here the same repeat is executed two different ways  The above repeat was cropped and adjusted to 16 stitch width and 8 row height, the file saved, and the process repeated  Using symmetry once more, remember to adjust the pencil size.  For the pinwheel shape I was unable to use color exchange successfully on the above images, but with the saved 2 colors indexed red and white repeat both img2track and ayab appeared to load the repeat successfully. The map color exchange was successful using the steps described at the top of the post when beginning with the repeat drawn in a black and white version.  

A different approach, experimenting with built-in brushes: symmetry preferences remain constant, the brush size is reduced. The results are best if the canvas is created in black and white indexed mode to start with, and shapes reduce with varying degrees of success. The numbers reflect brush sizes in each dot pattern. Different types of symmetry may be applied to the same image

For afghans or wall art, if one is attracted to large shapes, drawing in mandala symmetry on large canvas size is as gratifying and immediate as when using a spirograph, the results happen in seconds, these were drawn using 32 points. Steps may easily be undone along the way as one attempts to make the images more complex.

Visualizing maze or mosaic potential from tuck or slip stitch repeats

I have written extensively on mosaics and mazes, color separations required for drawing their motifs, and visualizing the resulting patterns while planning slip stitch or tuck repeats. A recent exchange with a knitting friend, Tanya Cunningham, brought up her idea of using Gimp to investigate the potential of self-drawn tuck patterns becoming pleasing mazes or mosaic designs in color. Tanya has worked extensively with img2track and can be found in the FB group and Ravelry. It had not occurred to me to reverse engineer designs for this purpose. Tanya uses Gimp in a different way than I do, I am hoping she will share her process for this purpose when documented.
I have grown comfortable and fast with the combined use of Numbers and Gimp to achieve what I desire in terms of color separations. At the moment, on the assumption that estimating the overall shape is the goal, a black-and-white processed rendering may be a sufficient representation of the result.

Punchcard books are a great source of “safe” tuck designs. The best are those that have columns one stitch wide by 2 rows high. They are also more interesting if there are areas of solid black. Patterns from publications intended for use on electronics are often color reversed to start with in order to minimize drawing pixels or to make the design easier to read and will have lots of blank areas. Punchcard users would need to punch the ground as opposed to the design, electronic users can achieve the goal by the flick of a switch or a quick software command. For my first series of steps and methods, I am using the repeat that appeared as a knit using different settings in the post on mazes and mosaics from universal patterns.
Presented on the left, the repeat would be suitable only for thread lace or FI with very long floats. Color reverse allows one to use it for tuck and slip stitch, whether in one color or with color changes every 2 rows. The color separation to approximate the result with color changes begins with the same process as that used for designing mosaics. Once the image is rendered as a correct B/W PNG with no apparent errors, it is copied and pasted on a larger canvas, and the mode is converted back to RGB. The red cells make it easier to keep track of rows that need to be color-inverted. Using the shift key and rectangle tool, multiple pairs of rows can be selected sequentially and color inverted. Beginning the selection with the very edge of the black squares on the left does not interfere with changing the color of the extra columns on the left side of the design. If pixels are added accidentally drawn in any of the 4 extra columns on the left, they can easily be removed when the completed conversion is cropped to selection for the final repeat. The completed color separation can then be filled to match imagined colors.
The repeats of the final knit pose the problem that results from working on a square grid and comparing the results, which usually form a rectangular one.
The representation of the linear patterns on the knit side of the piece cannot factor in some of the added distortions created by the stitch type used.
I process my images in Pages or Numbers, depending on which document contains my most recent work and happens to be open.
The final may be rescaled in Gimp.
Most knits approach a 4:3 ratio, with gauge variants in highly textured fabrics.  To preserve a clean design, tile and save the original, screengrab the resulting image, load it in Gimp, and rescale to that ratio.
Repeat the motif for the same number in both height and width when tiling it. The colored versions before and after scaling, compared with the slip-stitch swatch. It is possible to produce a rectangular grid to start with on which to draw in Gimp, but the larger canvas size occupies a significantly larger space on the screen, complicating the process. For small designs, however, that may be an option to give one the sense of aspect ratio for the design in the final knit ie in representational FI. To resize the grid in uneven proportions, the chain-link below the spacing values needs to be broken This repeat is designed for an electronic, and requires color-reverse.
Since it is 24 stitches wide it may also be modified and used on a card.
In this instance, the original marks for rows and stitches are single height.
The image is processed, matching the original, rendered double-height, color reversed, and then alternate pairs of rows were color inverted to render the repeat used in the test swatch Once again, the possible change in scale is estimated. The repeat though only 24 stitches wide, is 92 rows high. On the left the repeat is shown as it appears on a square grid, to its right is the scaled 4:3 version, in a pixel count approximating the size of the swatch. It takes a bit of squinting to see the pattern more recognizable in the longer repeat in the larger tile The swatch was pressed, becoming wider than when first off the machine. It was knit using the slip stitch setting, which could also be executed in a tuck stitch, and would both widen and shorten the fabric and make the purl side more interesting.
The software can provide a preview of the result far more quickly than knitting samples, but again, the previews are only approximations of the scale, and cannot show distortions to lines as one adds more texture.
Repeating the process starting with a diamond shape that as given is only suitable for thread lace or FI with problematic floats,  and with a check tuck pattern that may change in aspect ratio considerably when knitted The proof of concept swatch, knit in tuck stitch, begins to show the distortion by the stitch formations, textures vs plain knit, easily seen at the top edge. The bind-off is around 2 gate pegs in order to allow enough stretch.  Anyone familiar with either or both programs may find this a very quick way to visualize the scaling and moving of motifs within DIY designs and their possible outcomes prior to test knitting