To make sure color palettes are extremely accessible and easy to distinguish, they must vary enough in brightness. Differences in brightness are universal. Take any monochromatic color palette and test how it looks in Protanopia, Deuteranopia, and grayscale mode. You’ll quickly be able to tell how accessible this palette is.
From a purely mathematical standpoint, a color progression that transitions from light purple to dark yellow should feel roughly similar to a transition from light yellow to dark purple. But as we can see, the former feels natural, and the latter not so much.
from Delicious http://ift.tt/1UvjSsV