Real world example of "I don't even know what I don't even know"

[Faith No More]

Yeah, I'm admittedly ignorant of color-blindness. I'd be interested in hearing what anyone more knowledgeable  would have to say.

People seeing greyscale is actually only in extremely rare cases. For instance, I'm pretty damn colorblind. I scored a 1/10 on the eye doctor's color test, but I'm not even close to seeing greyscale. Let's say (and I'm totally making this up for illustration purposes) the normal human sees 100 million colors. Well, I see about 10 million colors (I don't know if that's actually the proportions, but you get the idea). So, I still see colors. I just don't see as many, and that results in me frequently not being able to tell the difference between colors that other people can. Green and brown are extremely difficult to tell apart, and blue and purple are pretty much just one color. I get a lot of other colors confused, but those are the big two. Also, when you look at one of those color paint swatches and see seven different shades, I see about three.

That doesn't seem like it would really make much of a difference, but the truth is that humans use colors in a way that can make it difficult for people that don't see as many to operate, especially at nighttime when the lack of light makes discerning colors even harder. I've stopped at blinking yellow lights and run right through blinking red ones. My first grade teacher chewed me out in front of the class for coloring a plum blue. So, even though I can see some color, it's not something I can rely on. Like with KUSA's images. At first, I could vaguely tell that there was a shape in those top images. I stared for a little while and after considering who posted it, I thought to myself, "Oh, I do believe that is supposed to be a cock and balls." In that bottom image I see nothing but random dots.

It's not about how the brain interprets colors, either. The rods and cones in our eyes are responsible for determining color, and people with colorblindness just have less of them. So, even though my brain is perfectly capable of interpreting all of those colors, the signal it receives from my eyes is flawed compared to other people. I have no idea how a pair of glasses is supposed to get around that, but I sure am curious to see what it would be like.