For this example let's assume a 48-end repeat for an 8-shaft loom, and a 4x4 initial. Illustrations have been enlarged 8-x for clarity; click to make full size. Start with a background colored in with bands 8 pixels high.
On a new white layer, transparency set to 50%, with black foreground color, and the pencil tool, 1 pixel size, draw a pattern line.
With white as the foreground color, clean the line up so that there is no more than 1 pixel per vertical column.
Bring the opacity back up to 100%. Delete the white pixels.
Using the colored bands on the background as a guide, cut and paste 8-pixel sections of the pattern line and sandwich them on top of each other, to accomplish the telescoping operation.
Restore the white pixels to the background and crop.
Copy black pixels to a new layer and wrap the new layer up one pixel (Filter>Other>Offset). Do this two more times, and flatten. This gives you a ribbon 4 pixels high.
Create a 4-pixel x 4-pixel file with the following initial, save it as a pattern preset.
Select the black pixels in your ribbon file and fill them with the initial pattern you have just created.
And there is your networked threading! Rotate it 90 degrees, copy it, paste it into the treadling area of your weaving program, enter any threading, turn the draft, and the networked threading is now in your weaving file.
Thank you, Ruth, for pointing out that Marg Coe has already figured this out independently. Her method is probably different from mine. The question now arises: why bother to do this at all in Photoshop when there are so many weaving programs that do networked threadings more efficiently? Answer: One never knows when a new procedure might be useful for some unknown future purpose. The intellectual challenge of figuring something out is its own reward. And finally, the freedom of drawing and manipulating pixels in Photoshop gives us patterns which might not occur to us in other software. So I'm filing this one away for another day.
For more information on network drafting, networks, initials, ribbons, telescoping, etc., go
here.