I don’t know enough about Butteraugli (in particular in the range of very very tiny differences in the image) to know whether it’s a reasonable metric for compa

I don’t know enough about Butteraugli (in particular in the range of very very tiny differences in the image) to know whether it’s a reasonable metric for comparing dithering algorithms. Why do you think this Riemersma method does better at that metric? Maybe it just keeps the diffused errors spatially closer to the original pixel?