Blue and purple are problematic because of the red component. If your color blindness comes from a deficiency in red then it's difficult. On the other hand, if

Blue and purple are problematic because of the red component. If your color blindness comes from a deficiency in red then it's difficult. On the other hand, if you're deficiency stems from lacking green, then blue and purple won't be as difficult. Red-green color blindness stems from a deficiency, and therefore some colors are aliased. It is not a substitution where the total unique colorspace is the same size but with different elements. The colorspace has is reduced. So it is not matter of memorizing that a shade of X is really Y. That may work in some cases that are likely unique to the individual, but there WILL be aliased colors.