Are there any debanding methods that add a point to the color channels?
E.g. A delta of +(1, 1, 1) in RGB space would have six intermediary (but not perceptually evenly spaced) values, e.g. (1,0,0), (0,0,1), (0,1,0), (1,0,1), (0,1,1), and (1,1,0).
This might be something dithering already does (and I just don't understand it).
It’s more or less linear—what you can do is dither in each of the R,G,B channels separately. To remove banding in an image, you dither in R, dither in G, dither in B.
If you take a gray value that is 50% between two gray values, and you use uncorrelated noise to dither, then the result will contain all (±0.5,±0.5,±0.5) delta from the original gray. If you use ordered (correlated) dither, you’ll get a subset of those 8 colors.
E.g. A delta of +(1, 1, 1) in RGB space would have six intermediary (but not perceptually evenly spaced) values, e.g. (1,0,0), (0,0,1), (0,1,0), (1,0,1), (0,1,1), and (1,1,0).
This might be something dithering already does (and I just don't understand it).