Yes, this is red. For most of you, I'm sure that's no big revelation, but, for those of us with a somewhat defective X chromosome (those of us who also happen to have a Y chromosome), that judgement can be problematic. Colour blindness is one of those fascinating phenomena. I'm red/green colour blind, but I can see that this is red (and, no, not just because it's a car's tail light). Other people classified as red/green colour blind might, indeed, judge it as green. I love things like this because they're such good illustrations of how our brains construct reality for us. We like to think "we're" in charge, the "we" in that being an independent entity, somehow above mere physical phenomena. Well, we're not. Our senses take in all sorts of data, report it to various integrating centres in our brains, and those integrating centres tell us what it all means. Not just what colour it is, or what it is, but how we feel about it, and what we want to do about it.

The brain's a pretty fascinating place, all in all.

Oh, and there are even a few folks with two X chromosomes who have trouble with this sort of thing, but, in their case, both have to be "broken" as far as colour perception's concerned, and that's relatively rare.