[nilsb]

Didder is fantastic. I'm using it to convert images to grayscale for use with Waveshare e-ink displays. I've found no other tool that both lets you specify a custom palette (without which the resulting image looks pretty bad) and is reasonably quick.

For future reference, this works beautifully with their 9.7" display: didder --palette '000000 111111 222222 333333 444444 555555 666666 777777 888888 999999 aaaaaa bbbbbb cccccc dddddd eeeeee ffffff' -g -i - -o - edm --serpentine FloydSteinberg

[sllabres]

Image Alchemy [1] Unfortunately not longer available. But one of the greatest image conversion software I know (including most of the here described algorithm for dithering and some more). And this feature set is from at least 25-30 years ago.

I'm always getting a bit nostalgia when I see these dithered images and remember the time then with the fascination for the opposite direction: 'true color... wow that would be great' ;)

[1] https://www.handmadesw.com/products/image_alchemy.htm