Gimp update for Mac 2


The previous post on the 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. According to the software download site for Mac “the currently available package provides GIMP 2.10.22 and has not yet updated to the latest version, GIMP 2.10.24. We’re working on that, please check back later.”
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  The black is the foreground color, the white is the background.
Using such small images I often work in 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 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. 

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. Default is 0, which means no limit, according to the image size.
Using a large image, testing 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, the maximum number of needles per pixels 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, 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, adding 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. Coming topics: saving brushes and patterns to one’s personal library


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