Error diffusion dithering should be done in linear color space to avoid the severe increase in perceived lightness of the dithered image. See https://surma.dev

Error diffusion dithering should be done in linear color space to avoid the severe increase in perceived lightness of the dithered image. See https://surma.dev/things/ditherpunk/ https://surma.dev/things/ditherpunk/ under "Gamma" for more info, and some example gradients that clearly demonstrate the effect.