2015-09-29, 12:34
I've done more A/B screenshots of color movies... there is literally no perceptible difference between dithering ON or OFF. After doing a difference comparison of screenshots of the identical frame there is, however, an imperceptible difference: a scattering of pixels throughout the image that are all slightly changed in color. And by slight, I mean something like an invisible change from RGB 69-91-130 to 69-90-129. There's no rhyme or reason to the changes, however.
Here's a difference map of the Disney logo:
Here's a difference map of the Disney logo: