This is the same e-ink device I believe that's in the Pimoroni Inky Impression.
I've written a Python program that anecdotally fixes the bias caused by the display for blues and greens, and dithers using an Atkinson dither. The code is based on some older Java implementation I wrote, but if you are considering a port to C
this is more succinct (entry point diffuse_image()):
The fix is to define the ink's blue as a slightly different hue than the device specifications, which tends to over emphasise it - improving it - when it comes to shades like sky blue (which the display can't achieve).
So instead of (perhaps) being quantised to green, which is closer colour match for the actual real hue, more blue is shown instead. Whilst this is incorrect for photographic colour accuracy, if you don't know what the original photo looks like it appears to be correct and better than the colour that is typically chosen (green).
Thanks for sharing! Atkinson dithering is a great choice for these panels. What the result lacks in detail it gains in contrast, and since e-ink panels don't have the greatest contrast ratios it's a good match.
Sierra dithering is a nice compromise between Atkinson and basic Floyd-Steinberg.
I've written a Python program that anecdotally fixes the bias caused by the display for blues and greens, and dithers using an Atkinson dither. The code is based on some older Java implementation I wrote, but if you are considering a port to C this is more succinct (entry point diffuse_image()):
https://github.com/KodeMunkie/inky-impression-slideshow/blob...
The fix is to define the ink's blue as a slightly different hue than the device specifications, which tends to over emphasise it - improving it - when it comes to shades like sky blue (which the display can't achieve). So instead of (perhaps) being quantised to green, which is closer colour match for the actual real hue, more blue is shown instead. Whilst this is incorrect for photographic colour accuracy, if you don't know what the original photo looks like it appears to be correct and better than the colour that is typically chosen (green).