I’m actually very colourblind, and it’s a weird thing, a confusing thing to explain. Lots of people think that I just see in black and white, but it’s more like confusing tones of colour. So, blues and purples or greys and browns may trip me up.
A “Normal” person is the sort of person that might be designed by a committee. You know, “Each person puts in a pretty color and it comes out gray.”