WORK IN PROGRESS
Lace knitting for many introduces knitting with 2 carriages for the first time. The lace carriage advances the cards, mylars, or programmed pixels a design row with each pass. In other stitch types the knit carriage, once it is set to select needles ie using the change knob on KC, in punchcard machines,
or KCI for end needle selection, KCII for no end needle selection in electronic models, also advances the pattern a row with each pass. The advances happen in Brother machines when any carriage locks onto the belt and moves past the center 0 marking as it travels from one side of the stitches in work and past them to the other.
Electronic and punchcard published lace patterns may be used in both machines as long as when punchcard models are in use, the pattern repeat is a maximum of 24 stitches wide or a factor of 24, such as 2, 4, 6, 8, or 12 stitches in width for each complete repeat segment. This exchange is possible because the knit carriage does not advance the pattern repeat in both models, it is left set for and performing plain knitting, with the change knob set to N-L.
When the knit carriage(s) is (are) also set to produce patterning, extra caution needs to be taken with the alternate carriage being off the needle bed so both carriages do not lock onto the belt, which will then be anchored on one side, and pulled toward that spot from the opposite side, possibly causing it to break. One instance in transfer lace knitting when the knit carriage also selects needles is in knitting automated edgings.
Many other stitch types may be knit with 2 knit carriages selecting needles from opposite sides. It is one way to have frequent color changes without using a color changer, tensions and cam button settings can also be different. On an electronic machine, each pass of each carriage advances the design by one row. Here patterns stop being interchangeable. With 2 carriages selecting needles, when a punchcard machine is used, as the alternate carriage makes its first pass from the opposite side, the card does not advance, so the previous preselection is repeated. To use a published repeat for either machine on the other, the repeat needs to be adjusted.
If one of the two knit carriages is left set to N-L, it will not advance the pattern, adding an easy to add plain knit rows between patterned ones without having to alter cam button settings or the programmed repeat.
In transfer lace knitting, there are many considerations when attempting to represent carriage movements for both carriages in a single chart when the knit carriage is not also selecting in pattern, but simply knitting and not advancing the repeat. The first illustrations use the machine knit repeat developed from a hand knit pattern inspiration many a year ago 2013/12/05/lace-mesh-motif-charting_-mac-numbers.
Since then software versions, computers, operating systems, and my use of them have evolved and changed. I have edited the post with additional information, inked in a different color.
Experimenting with DAK has brought me back to thinking about the issues in charting lace fabrics in particular.
Lace knitting tips including card and electronic markings for transfers and knit rows
Mesh grounds: 2017/07/29/to-mesh-or-not-to-mesh-5-design-repeats/
Info on lace meshes for both grounds and patterns 2021/05/12/to-mesh-or-not-to-mesh-8-more-numbers-meet-gimp/
Two of the posts on using Studio repeats on Brother brands:
2019/02/23/revisiting-use-of-lace-patterns-studio-vs-brother-machines/
A Studio lace card with single blank rows between transfer segments knit on a 910
No symbols are used in this chart, it is intended for use on Brother machines. The red cells represent transfers to the left with LC operating from the left, the green cells represent transfers to the right, grey cells indicate knit stitch rows.
The knit rows in most lace unless the pattern is combining KC needle selection for slip, tuck, FI, or weaving do not advance the pattern rows.
LC actions are marked on the left, the KC ones on the right
The LC makes 4 passes:
1: preselects for transfers to the left as it moves to the right
2: transfers to the left as it returns to the left,
3: transfers to the right as it moves to the right, there is no preselection for the next row
4: moves back to the left with no transfers or preselection
The KC follows with 2 knit rows. In the chart for this pattern, representing only the repeat, there is no room to indicate KC passes on the left-hand column
The appearance of the chart or template changes if 2 empty rows are added to represent the KC passes. It may help one understand what is happening but in Brother machines, 2 of the 4 blank rows here would need to be eliminated for the pattern to knit properly.
Transfer design segments may vary considerably in the number of lace passes and transfers between knit rows. In the pattern below, only 2 rows of knitting are completed after 20 carriage passes, the bottom half is repeated X times, the top half X times, adding even more complexity. Depending on the knitting machine model, the pattern may also need to be mirrored to knit accurately. 
Published punchcard books offer patterns with potential errors usually sorted out. Both punchcard machines and electronics scan the card or mylar inside the machines, several rows down below what is visible to the knitter at eye level on the exterior of the card or mylar slots, so markings on both need to be made accordingly. This is a fact that needs to be considered with cable downloads of the same patterns if entering memos for knit rows. In the case of punchcards, Brother reads 7 rows down, Studio 5. In fabrics other than lace adjusting for the brand is straightforward ie to knit fair isle, tuck or slip pattern if using a Studio company supplied punchcard repeat, simply start the Studio card on row 3. If punching your own, design rows match, if the blank card is marked for Brother, the numbering is accurate by default. Brother cards begin with pattern selection, Studio brand with 2 knit rows. In this repeat, a mesh repeat is created first moving to the left, then to the right, the 2 knit rows follow 2 LC passes for transfers to the left, 4 LC passes for transfers to the right. Brother row one marking is underlined with a blue line, Studio with red 
A Studio repeat adjusted for use on Brother also illustrates that the number of knit rows are only two, the LC passes can vary in number between knit rows. Here LC passes are marked with outlines around pertinent row numbers on the right 
Brother vs Studio: extra knit rows in Brother are not physically left as blank rows in cards, the rows for KC are still 2 blank ones, while in Studio cards there is a blank row for each knit row in the pattern. Both these samples have a 6 knit row sequence. Because Studio begins with 2 blank rows, in the repeat on the right only 4 rows are left blank at the top of the repeat. 
Adjusting for extra knit rows, Studio to Brother 
These samples are from Brother punchcard volume 4:
single blank rows between transfer segments 
varying numbers of blank rows between repeat segments
multiple rows of knitting (8) marked aside a single pair of blank rows 
Some electronic examples using the 2-row spacing between transfer segments: this is a page directly from the Stitchworld electronic pattern book 
a pattern published on a full Brother mylar sheet 
this is from a studio mylar, the same holds true in terms of the number of empty rows between transfers, 
that is the reason why most transfer lace patterns unless they are designed as studio simple lace where transfers are made with each carriage pass, patterns may be exchanged between both brands, the only difference being studio starts with 2 blank rows, ends with transfer markings, Brother starts with transfer markings, ends with 2 blank rows.
Electronic repeats are interchangeable after taking that into account, but not mylar sheets in respective brand mylar readers because the number of rows below eye level where the electronic readers scan the design is also different between the two brands.
Transfer lace may also be combined with other stitch types, each with its own considerations as in these instances both types of machines have the KC selecting needles as well. The punchcard published patterns need to be adjusted for use on electronic models. As already mentioned, punchcards do not advance with the first pass of the alternate carriage from the opposite side, while electronic models advance a row with each pass of both carriages:
adding KC slip stitch selection for creating ruffles and doilies
tuck stitch
weaving 1, weaving 2
fair isle
The lace module in Dak will do the work for the knitter once the pattern is entered as symbols. Eyelets will be represented in single rows, a shorthand version of the previous samples. Reviewing how the transfers would appear on the knit and the purl side respectively. 
The LC can move only one needle at a time, so when multiple needles need to move to place the eyelets properly, the options are to use a hand tool performing the moves or to develop a pattern with multiple transfers in each segment of the final repeat. The full repeats are often very long.
There is a handy option in Dak when thumbnails is chosen from the image menu, one can browse through saved folders containing compatible file-formats including the images in those Brother magazine downloads. The small preview will identify the specific file size. When you left-click on your choice, it will appear enlarged at the bottom left of the view window, it has been moved from its corner in my screengrab, 
left-click OK on the enlarged image, it will open in the program window. Minimize the size until no further reduction is allowed by using the magnifying glass or the scroll function in the mouse. This is a different operation from scaling the original to a different size. The save-as option for the image offered at that point are:
For choices emulating export in other paint programs, right-click on the image, choose copy, open a paint program (Arahpaint is my favorite at this moment), and from its image it menu choose paste. 
Using Arah’s color exchange, the image may then be converted to black and white for 2-color work and is saved in a format usable with other software and in other machines. 
but if the image needs to then be reduced to BW, Arah is the easier and predictable tool to use.
It is useful to establish working history using the same design motif. In the first image, left-click on red, the from color, right-click on white, the to color, click on the double arrow to make and apply the change
The print dialogue allows for saving patterns as bmps. 
from the manual 
If there are no “short” needles in the image being processed as in the last screengrab above, there will be an error message onscreen, pointing out problems in the numbers of colors present in rows ie more than 2 for FI. This is fixed by clicking on either the “needles” of one of the two active colors in the yarn palette to make one color the ground, the other the contrast. The results from this process for printable bmp files are shown below, not for a bmp that may be used to knit the pattern on an electronic machine using a different download method. Here the resulting stitch pattern picture is shown in color reverse as well. 
At this time I am continuing to knit on my machines with punchcards and using Ayab, or img2track on my electronics, have no immediate plans to change that, hence my interest in using DAK software features while keeping in mind the possibility of using the final repeats on other machine models.
DAK row numbers do not refer to design rows, they reference row counts as would be seen in any row counter registering carriage passes
If a symbol is missing from the drawing, the program alerts the knitter to the error. Here there are no eyelets represented. 
If the content is considered accurate, this window will appear, the safe button will be highlighted, click OK 
wrong side facing is chosen for the purl side view. 
Stitch pattern print previews, using default settings for layout:
Numbers on the left, correspond to carriage passes, not design rows. While the electronic printout differentiates between rows for use of the LC and KC, leaving the KC rows unlabeled, that distinction is not made here.
choices can also be made on how to represent stitch units 
Regrouping after a review of my repeat from Softbyte support: the original stp has an error in it on row 11 where yours truly had eyelets being created by having the same stitches moved in opposite directions in the same row. It is interesting that I was able to save the stp without receiving an error message as seen in this instance below when the pattern was being redrawn with transfer symbols on the wrong row, 
Please see the next 
The electronic preview continued to have a series of 4 blank rows between transfer segments. My repeat received no warning as to problem rows or symbols, saved as an stp, the associated print preview had issues again. Published patterns may also not always be correct: the renderings below begin with the DAK punchcard template on the left with confused numbering, the extra empty row at the bottom of the repeat eliminated, and another 3 blank rows occur at the top of the sequence. It is followed by the published pattern associated with the repeat, pixels are then marked for left and right transfers, followed by my amended repeat, which when knit on the 930 required mirroring. 
The convention for lace designs is that they contain an even number of rows, the one on the right is 47 rows, knits properly, is suitable only for a border. Here I knit a couple of extra rows and reprogrammed row 1
Letting the repeat knit as a continuous pattern with a total odd number row count reverses the direction of the transfers, resulting in mispatterning and multiple side-by-side empty needles in the subsequent full repeat. Changing the total repeat to 48 rows places transfers overall in matching directions. The small flower shape could be moved up and its transfers reversed, but in this instance the 48-row version, though transfers were made in the correct direction, still did not produce the continuous pattern alignment I would prefer. The challenges in DIY lace patterning are many.
The information available to me as I began this post:
When exploring design potential in any paint program, it is best, to begin with, to use a small repeat that can be clearly identified when tiled in various configurations, resized, and pixel edited. If drawing is with the goal to produce a BW bitmapped image for download of 2-color patterns, drawings can happen in those colors to start with. If color separations are planned in the development of the design, then 2 color images including black may be preferable.
To work on the image, magnification will be required. This may be achieved in two ways on the Mac, one is to click repeatedly on the magnifying lens icon in the toolbox, the other is to press any number from 0 to 9 on the keyboard, the zoom will instantly change for 1 at 100%, to 6 for 600%, to 0 for 1000. The latter is minimal for building repeats on a viewable grid, the magnifying lens may be used to reach a comfortable starting view. The zoom level for both increases and decreases may be changed during drawing operations as well.
In addition to the image grid, like Gimp, ArahPaint 6 also allows for positioning aids: guides. They are horizontal or vertical lines that are temporarily displayed on an image. To create a guide, double click on the dark blue arrow displayed on one of the rulers in the main window. The guide is then displayed as a dashed line, which follows the pointer. To move a guide after it has been created, hover a mouse pointer over the blue arrow and click and drag it to remove the guide to a new location. To delete a guide, double-click on the arrow. After a guide is created, another triangle in a different shade of blue appears below it. Use that to create the next guide, repeat as often as wanted both horizontally and vertically. To remove all guides choose View, Remove Guides. 
One use for the lines can be to mark plain knit rows between transfer markings in lace punchcards as illustrated in this Gimp image 
Foreground (upper square) and background color (lower square) are used in drawing operations. They are numbered 1 and 0, not to be confused with the same numbers assigned to colors in the working palette. The starting palette may be altered to include black. Double click on the foreground color at the top, the #1, not in the space below the palette icon. A color selection window will appear, choose, click OK. This change is lost if one quits the program. 
If satisfied with the drawn repeat, use the selection tool to isolate the final motif. 
Pillar repeat also using offset in pixels 
Other offset options through the use of fractions
Playing with mirroring positions, producing a minimum 2 by 2 repeat, 
the result looks akin to the pillar repeat drawing above, but tiling again to check for alignment may yield surprises that can be viewed as design features or errors, 
Repeats may be built in a more controlled manner using the image duplicate menu, its symbols immediately reminded me of the Passap Alter Direction options: 
a half drop was added 
and the repeat was tiled to test alignment 
The duplicate tool enables the repeat of an image or part of an image in a fast way. All duplicate tools with the exception of Mirror X-1 and Diamond work similarly to the drawing in repeat tool if the new picture option is enabled. The mirror X-1 works the same as the normal mirror, except the last pixel of the image is omitted from the image 
Eliminating those double pixels can be achieved by cropping. The first mirror is for Y-1, the cropped image is tested for tiling by drawing in repeat 
Drawing lines: use the straight-line icon button to activate the tool, select the line thickness by selecting a number of pixels to be used then move the mouse pointer to a line starting point on the canvas and press the left side of the mouse, dragging it until the line is of the desired length and angle. When the line is at that desired length release the mouse.
The thick lines option works only at line width 1, which will keep the single pixels connected 
If you double click on the line icon, the Straight-line icon is activated. Now you can draw horizontal, vertical, or diagonal lines. If you move a mouse horizontally—it doesn’t need to be perfectly straight, the drawn line is horizontal. If the angle between a line and the horizontal axis exceeds the angle of 23 degrees, the drawn line will be diagonal at 45 degrees. If you move the mouse toward the vertical axis, the line will be drawn as a vertical line.
The same process, using an 8X8 repeat drawn in repeat X3 in width to 24 stitches and X5 to 40 rows in height meeting the punchcard minimum height 
Finding the repeat first on the complete resulting new image on left and testing its tiling, followed by finding the repeat again, cropping to the selection and tiling that as well on the right 
If the goal is to knit a scarf, 72 stitches wide, crop either repeat to a chosen 72 stitches in width, tile in length in either program to visually check alignment. If knitting in DBJ for approximately 1200 rows is the goal, one may obtain a visualization of the results ie for 1296 consecutive rows. 
A black pixel border could be added to the 72 stitches by copying and pasting the image on a larger canvas that will accommodate that border, or the border may be added by filling in pixels vertically to the edges of the original. Some repeats to play with: the 120 X 96 png 
The bottom half, 120 X 48, isolated in Gimp, 
tiled in length X4 to get a sense of some of the possible differences I c
I can see the process becoming addictive once a single personally pleasing starting repeat is developed, and its, in turn, becoming a possible source for collections of designs
The color exchange was easy and straightforward with self-drawn images in the opening palette when creating new documents in Gimp. It failed when working on a segment of published patterns. The Arah manual helped me find the solution. Converting the images from true color mode to color palette mode: the original image and its palette, this is not a “correct” working repeat, 
Converting for use with an expanded palette
To change the color of the foreground, double click on it, choose black from the upper left corner of the colors window, the image and its foreground color will change accordingly. 
The successful exchanges 
This repeat would work fine with a reduction to 3 colors, but the proof of concept uses a reduction to 4 colors for both repeats. The two shades of green will need to be exchanged separately, each shade is processed using the sliders on the far right, also note the crosshair. 
while ArahPaint will multiply the motif cleanly only in height when needed, seen here with the original multiplied both X 2 and X4
The Arah scaling appears to be quicker and far more accurate also when used on some published images that would require a lot of clean-up after resizing in Gimp. That said, when working with very large images Gimp offers the opportunity for controlled scaling to any size, keeping the image aspect ratio or not. This reference is described in translation as a pattern design course for Silver Reed knitting machines. 
The publication offers many large-scale repeats that are suitable for punch lace, but also for what translates to “braided patterns” which when studied may be intended for fair-isle with enormous floats or for DBJ. No stitch and row counts are given, the goal is to match the manual 54X56 stitch and row count.
In Gimp, reducing colors: A 
Use scale image to desired dimensions, checking first that values are a full multiple of the expected final repeat pixel count. If not, scale first to a full multiple of each value with aspect ratio off (broken chain link), then scale again with aspect ratio on (intact chain link), edit with a superimposed grid, cleaning up the repeat: C. 
single click on the yellow above to place it in this selection, double click on it 
use sliders again to achieve the white, click OK
ArahPaint will also scale larger images in pixel units. Resizing may be achieved through the use of the image menu Resize option, 
I found the final Arah scaling to be less accurate and requiring more clean up than the repeat obtained using both programs 
Planning a repeat suitable for a punchcard, the uncropped repeat F is opened in Gimp, and pattern fill is used in white areas to ready the file for tuck knitting. The image is then map tiled to check alignment once more, and if satisfactory, it can be saved, ready to be knit 
With experience, one can quickly imagine ways to clear errors and alter images. Electronic machines free us from repeat width constraints. Widening the zag repeat to 48 stitches, working in Arah, check vertical alignments first, 
Pattern fill may be accomplished in ArahPaint using brushes made from selection and then enabling those brushes with bucket fill. This functionality is shown in this video: 
Working on a possible tuck repeat using only Arah Paint: draw and save the image you wish to superimpose on the ground and save it. I chose to use the color red for visibility. Draw a new image, keeping magnification constant, ie using 0 for 1000 X. Draw a repeat unit for the brush you wish to use, choose repeat from the View menu, click on the stamp icon shown outlined in red, and the available brush will appear immediately below it 
Lots of knitters appear to be interested in large, nonrepetitive images. Depending on the machine used and its memory, the repeat may need to be split horizontally or vertically. Before electronic machines, many art-to-wear pieces were created knitting repeats broken down horizontally into the punchcard widths, completing the height of each panel and then joining the strips together. Nowadays there are online tools for many tasks including dividing large images. For DIY, in the first instance, Arahpaint is used to split the “large” file in half horizontally, the resulting image saved. The action happens from left to right, so to achieve the split for the second half, the full-size original is flipped horizontally, split, and flipped again. Followers of my blog have seen the images of my friend Rocco recurring intermittently over the years. Dividing the image horizontally 
The same may be done vertically in a matter of seconds beginning with Image, Halve Y, and then using the mirroring tool 
Mosaics: draw the desired repeat in Arah, double it in height, save the image, open in Gimp and proceed with mosaic color separation 
The plan is to create a repeat which may be knit using color changes every 2 rows. Each design row knits each color twice, so the standard built-in KRC separation is not a consideration, though the same cam settings may be used in those fabrics as well.
End needle selection is canceled, the first and last needles are in work on each side on the ribber knitting every row, the first preselection row is from right to left, cam buttons are set after the left side is reached. Knitting in these samples began with the blue yarn in the number 2 position in the color changer. The ribber remains set for knitting in both directions throughout, the images on the right do not reflect the amount of surface 3D textures.
Lock settings are easier to achieve on the Passap than switching out cam buttons in Brother machines. This was knit using 4 carriages. Color one knits with the main bed set to tuck both ways, color two knits with the main bed set to slip both ways. The slip stitch reduces the width of the fabric considerably 
Here each color alternately tucks and slips. The choice of cam buttons matters, tucking first from left to right, slipping from right to left, with cam buttons set COL after the first preselection row 
This last cam setting appears to my eye to produce a texture “close enough” to the inspiration fabric. Attempting to add more colors: the repeat, D, is still 18 X 88 but is now shifted slightly. 
The existing repeat may be reduced further to 18 X 64, eliminating some of those extra rows in the center of the chevron shape 
Whether or not the design is intended to retain chevron shapes in alternating textures, actions may be plotted pre knitting in any way that visually makes sense to the person designing the pattern and tools available to them. 
Reversing the png so that the more textured stitches will begin with the color in yarn position 1
Using either repeat, color changes now occur after every 32 rows knit. Another color change location clue is in the needle selection change above and immediately following the red border in the chart on the left. 
Adding colors can be planned cautiously or allowed to happen randomly depending on the preferences of the designer and end-use. Ribber fabric designs are not visible until several inches have been knit, too late to catch color sequence errors. Some machines allow for memo placements or sounds to help track color changes, but only within the initially programmed repeats. A quick spreadsheet can provide customizable checkboxes or added information. For an attempt to retain chevron shapes in different textures: 
A PDF including row numbers and space for notations 
The test swatch and observations: patterning was begun with color 2, yellow.
Continuing on a 24 stitch repeat, the original design may be rendered at double height and separated once more, doubling the separation height to 96 rows 
There are days when either or both machine and knitter need a break. At the start of the first swatch, the cam buttons were not set, resulting in plain knit stripes. At its top, the purple did not get picked up properly from the color changer, and the knitting of course fell off the machine. On a second try, the same issue happened again with the purple yarn. Multiple incidences of such events were fondly nicknamed “dropitis” by my students. The test is on 24 stitches, the width of a single repeat, the triangles are much more balanced in size, this knitter is putting this pattern to rest. 
Another even more complex inspiration from a sweater attributed to Falke, Spring 20 collection, using similar stitch structures, but in addition, also transferring stitches between beds exposing a purl striped ground.
Adding needles out of work by simply choosing to cast on and working on every other needle it does not matter whether even or odd needles are in use, the pattern will be identical but simply shifted over by one needle. For frequent color changes, make the first preselection row toward the color changer to start with, keep notes as to where the repeat color selections happen as experiments are expanded, evaluate color choice as a third or even fourth color are introduced 
the third tuck row on the machine 
the fourth tuck row with needle preselection for the first all knit blue row 
Two from one: the same tuck repeat was altered by changing the needle out of work arrangements. Slub yarn may be used but changes the value of the lines formed by the floats created in the needles out of work gaps. 
Chain cast on 2 in work, 2 out of work, end with 2 needles in work
Number 11 is a close relative but worked on every other needle 
The rayon used in the previous sample, and a 2/8 wool, were less successful than a 2/11 acrylic in knitting the swatch. The stitches need to be as tight as possible while also needing to be able to knit off properly
The same directions apply in this instance, the first sample worked with no needles out of work 
This knit begins on every needle 
Eliminating those ladders or floats, here eyelets are created where stitches are held for two rows. 
push first 2 of needles out to hold 
COL knit 10 rows, bring the third pair of needles into work, knit one row
Shell shapes: #4 and # 20 directions are given in the 2017 blog post 
Some of the trims in this pub may be far more easily and quickly executed using tuck stitches.
For some reason, I found the commands erratic when working on the translated version of the site, fared much better in the original language publication.
Screengrab the final image surrounded by extra white cells, open it in GIMP. Change the mode to indexed BW, crop the file to content thus excluding any extra white cells, scale to the original design’s 24 by 74 dimensions. Punched holes are now pixels; export the knit-ready BMP.
Getting a preview of how a finished garment might appear, here the tiled version is 192 pixels in width and one may glean some idea as to whether that repeat should ever really be used in a sweater or even a blanket. Further image scaling or cropping can happen based on the knit gauge. 
A very quick rendering imagining pattern and color placements using a simple sweater outline 
Collections of every other needle repeats for processing with a similar approach may be found in these volumes, available for free download
Both volumes include accompanying swatch illustrations.
For a better, printed match size, after capturing the image from the PDF for a single page outside image edges, opening it in Gimp, cropping it to content, it is then possible to scale the results to measurements of a factory punchcard equal in width and adjusted for the number of rows in the image. My card required print measurements were 14.1cm by 26.1. Scaling executed with aspect ratio is too long. 
breaking the chain-link, removing size constraints 
single click on the filing cabinet icon on the right, 
double click on the patterns folder, its own window will appear, 
and the new folder will be added within the brushes one 
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 
When exporting self-drawn brushes, the option is offered for adding spacing surrounding the shape, here a 10% addition was chosen 
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 contents of the newly created folder 
Use Windows, Dockable Dialogues, choose Pattern. The patterns will show on the right
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.
Foreground and Background colors: in RGB Mode, click on the foreground color to select a new color for the grid, click OK 
This command is found in the image menubar through 
You can create as many guides as you like, positioned wherever you like.
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, magnify at least X 800 for a grid view.
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 the 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, the color exchange window will display the new “to color”. Click OK, 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 Giles
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.
Developing custom palettes in order to visualize different colorways while using the same repeat:
this window will open with selections for possible palette choices 
click on your choice, then click on the palette icon, your color choices will appear, click on the white, to create a new background color.
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 
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 
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. 
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. 
The appearance of the final repeat when color 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. 
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, 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”.
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.
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 
Using that small triangular 8X8 repeat
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 
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. 
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. 
Nearly all my previous dbj pieces have been knit on a Passap E6000. The 930 experience for such repeats is new to me. With some help from Tanya Cunnigham in reviewing steps required when using img2track, I returned to cellular automata repeat saved years ago.
That provided an opportunity to decide I preferred the reverse color placement as well as wanting a thicker ply for the white, resulting in twice the fun with 2 colors, and another scrapped sample 
I was able to achieve a reasonable repair on the knit side, but the birdseye pattern on the reverse is a bit scrambled. 
There is also potential for exchanging colors to get a sense of how the pattern might appear in different colorways