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Next I took it down from 8-bit/256 colors to 4-bit/16 colors. As
mentioned before, thats a no brainer for a black and white image. That
reduces the file size even further. Then just for looks I changed some
of the 'almost' white or 'almost' black pixels to true black and white
leaving the greys in the middle of the range.

If you had taken it all the way to 2 colors (B & W) the GIF compression would
really have been something. FWIW, the enlarged schematic of the 4581 TX
compressed instantly to 12K, though still 841x411. Although the original was a
full-color JPG, there were apparently only black and white pixels in it.

When converting to GIF, GIF has to figure out ahead of time how many unique
colors re in the image, and it quickly found there were only two, so it went to
B&W GIF, which is very efficient. --MikeK.

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