"Why is Facebook blue?... It’s because Mark Zuckerberg is red-green color blind..."

"... blue is the color Mark can see the best."

That factoid begins an article about the use of color in branding, which does not otherwise involve the topic of designing color images with knowledge of how it looks to people who see some but not all colors. The article gets into assertions about what women like and what men like. Both respond to blue and green and are repelled by orange and brown, but women go for purple, which men don't like, and men like black while women dislike gray. That's sort of interesting, but it's much softer information than the hardcore physical reality of red-green color blindness.

Is there software that lets you check what your design looks like to someone who's red-green color blind? One answer, I guess, is stick to blue. But it seems to me that there are many blues, including blues that lean toward red (before you'd say purple) and blues that lean to yellow (before you'd start calling it green). A person who's not red-green color blind might think that's a really lovely blue at the very point where it might look ugly to a person with red-green color blindness.

I've been thinking about this topic a lot because I've been losing my sense of smell, to the point where I'm smell-blind — anosmic — in some sectors of the sense of smell. It would be one thing to have no sense of smell at all, like complete color blindness. But when you have partial perception, you care about the part that you have, but you'd like a good experience with it, but other people, who may be providing the experience, don't know what it's like for you.