The last related post, 2023: Gimp 4, pattern fill, dithered portraits, and more. It includes methods for removing backgrounds from the initial images i.e. 
The draft for these explorations began more than a year ago, and turned up when I circled back to testing additional Gimp features.
Two Gimp updates in September 2026, the first, 3.2.4, and shortly after that, 3.2.6.
3.26 brings up this window on Macs when initially launched
select deny and keep working. The request does not recur after quitting and relaunching the app.
Since I began using ArahPaint for developing my design repeats and color separations, there are only a few Gimp features I still use with any regularity, but as with other rabbit holes, I return to testing when driven by curiosity for how features I am not familiar with may work and have to offer.
I am presently working on a Mac with an M4 Chip, OS Tahoe, 26.6.2, keep circling back to Gimp 2.10, the last predictable and bug-free version I have tried for some of its features.
A recent tool shared in forums that is being tested for dithering and separating multiple-color large, non-repetitive designs, i.e., portraits, stirred my pondering on some of the possibilities to consider before executing them in DBJ on 4.5 mm home knitting machines.
The width of the repeats is, in theory, limited by the fact that such electronic machines have 200 patterning needles available.
The results are very low resolution, but can be improved by using a larger number of stitches and rows in the final piece.
Any image can be split into panels, followed by knitting them individually and joining them upon completion.
Color Palette choices may not match yarn color choices, and if they do, yarn thickness must be considered.
Printing a large-format version of the image in any color combination helps to visualize some of the potential results of knitting it, i.e., clarity and easy identification of smaller shapes, particularly in portraits.
A list of free online dithering programs, some with BW results only, may be found in the post on Online Pattern generators, hacks, free KM manuals, and more.
Splitting images
A fractal-inspired randomly chosen image, 
with a change to indexed, 4-color Mode. 
Gimp does offer dithering options, but I prefer the results from using online tools.
Changes in the original aside, 4- color and 2-color BW dithered versions. 
The colors in the triptych are deceptive. This is the BW PNG for the image on the above right, 192X248. 
It may be divided based on the knitting machine’s available storage memory, knitting method, or other personal preference or end use.
Go to the top menu and select Image > Guides > New Guide (by Percent).
Choose Horizontal or Vertical, and enter the percentage where you want the split line (for example, 33.33% or 50%). Click OK. Repeat to add all the necessary guides.
I typed in 33.33 for the first guide, 66.66 for the second, deciding to split the file into thirds. 
Go to Image > Slice Using Guides (or Filters > Web > Slice in some versions).
Choose the destination folder, image format (i.e., PNG), then click OK or Export to save the individual pieces. 
May 2025
Gimp March 16, 2025, has many menu and command changes, making some reinterpretation necessary when following previously published blog posts, and a quick tutorial.
I have encountered several issues with familiar functions; I have both this and the 2024 versions available.
Experimenting with transform/distort: you can access the Warp Transform tool by selecting Tools > Transform > Warp Transform from the image menu, clicking the tool icon in the toolbox, 
or pressing the W keyboard shortcut.
The 2025 new icon. 
Potential results. 
The method options. 
The brush size can be image size, rectangle, or ellipse-select to distort only.
“Abyss” is a term used by GIMP developers for “data outside the input buffer”. The warp tool moves pixels from one point to another. Some pixels may come from outside the layer boundary. These pixels don’t actually exist anywhere, and therefore don’t have any associated color; yet, some color must be assigned to them.
The abyss area refers to the area outside the original layer boundary when pixels are displaced or warped.
“Abyss policy” has a drop-down list that allows you to fill empty areas in different ways:
None: this is the default option. Empty areas are transparent. An alpha layer is necessary for this option. Any pixel dragged inward from the outside boundary creates transparent space.
Clamp: each edge of the transformed layer stretches out indefinitely, so, for example, a pixel to the left of the layer boundary has the same color as the leftmost pixel of the layer with the same y coordinate. An alternative way to think of it is that each pixel outside the layer boundary has the same color as the closest pixel inside the layer boundary. The edge pixels stretch out in straight lines to fill the empty borders.
Loop: the transformed layer repeats itself in all directions, so that, for example, falling off the right edge of the layer takes you back to the left edge. The texture tiles seamlessly, pulling the texture from the opposite side as you warp.
Black, White: these options are similar to “none”, but use black and white for out-of-bounds pixels, instead of transparency.
A glitched effect pattern knit could be created on shapes, matching pixel numbers to those of stitches and rows in the planned piece.
Click and hold down the mouse in the center of the pattern to apply the twist effect.
Working on a 120X120 file:
using the default settings: drag and release the mouse to draw across the full-size file in straight, circular, clock, or counter-clock movements, until satisfied, 
or use the rectangle or ellipse select tools to distort only the respective areas on a unaltered background 
pixel size of 28
A seasonal BW image with its background color to alpha was superimposed on the simple brush-filled ground in the program’s default position, then on a warped >transformed one. The file is blanket size, 180X180 pixels, with no added clean-up. 
The skull was scaled to 59X84 pixels to preview a possible scarf design. With such reductions, some skull definition is lost while the striped background becomes more dominant 
October 2026: the pertinent, clearly presented information for the manual for version 3.2.6 https://docs.gimp.org/2.10/en/gimp-tools-transform.html#gimp-tool-transform