The examples of dithering that look low-contrast and overly bright are due to incorrect gamma. The diffusion algorithms don't inherently make images brighter.

The examples of dithering that look low-contrast and overly bright are due to incorrect gamma. The diffusion algorithms don't inherently make images brighter. They require working in the right color space, linear light in this case. This color space error is less visible when dithering to many colors, because the difference between the most similar color and dithered color is small, so the (incorrectly) diffused error is small. But dithering to 1 bit is the worst case.