August 2009 – Colblindor

Certain jobs in the film industry definitely require very good color vision. If you need to adjust specific hues and find a good balance of the colors in a picture, color vision deficiency would be quite a big handicap.

Just the other day I took a picture of a rainbow. It was such a beautiful one, but I couldn’t see the color spectrum so I had to ask my son, if it is really a nice one where you can spot the whole color spectrum. The same would happen if I would work as a professional in the film industry: Either I could ask somebody for help or I just would fail. My color blindness is just to strong to deliver good work.

Truelight Color Vision Test — Truelight Color
Vision Test

FilmLight is a leading company in the film industry and provides a simple online color blindness test on their website. This way you can perform a first check if you are ready to work with moving pictures. Can you spot the T? Check out their website to see the whole Truelight color vision test picture.

This color blindness test picture consists of three lines each showing six T’s. Four of them should be visible and you should be able to tell their orientation. You should also be able to guess the fifth correctly and the sixth is just visible under perfect conditions. The three lines of T’s relate to the three different types protan, deutan, and tritan color vision defects. The test is based on the color blindness confusion lines.

You can’t see anything? — No worries. I can only spot two T’s in the last line. Only if I bend my laptop display back and forth I see two more T’s, but not more.

If you did like this kind of test make sure to check out my color blindness tests or have a look at some other color vision tests online available.

Are you colorblind? No, you don’t think so? — I am sure you also have some form of color vision deficiency or colorblind sensations. You don’t believe me? I’ll prove it in the following article.

I would like to show you four types of color blindness which are true for almost all of us. Starting with a very simple form we will definitely get into more details when it comes to small-field tritanopia, which strongly supports my statement that everybody is colorblind.

(A) Colorblind in the Darkness

When it is getting dark at dusk colors start to fade. You start to mix up colors and are not so sure any more when it comes to naming a specific color. So one could say that everybody is colorblind in the darkness.

I know this is not such a strong argument to support my statement, but it is a very good example to get an impression of how it feels like if you would have some form of color vision deficiency.

(B) Ultraviolet and Infrared Blind

Non of us can see both far ends of our color spectrum: infrared and ultraviolet. We name those colors but we can’t see them. This doesn’t necessarily means we are colorblind if nobody can see them anyway. But there are creatures who can see those colors.

A lot of people heard that bees can see ultraviolet light; which is true. But they don’t have a broader color spectrum as they also have only three different color receptors like people with normal color vision. Bees see less reds and more blues, that’s not really better than us isn’t it.

But there are some fish, some turtles and the whole family of birds who can perceive our whole color spectrum and also ultraviolet light. Birds have four different color receptors (tetrachromats) and clearly can see more colors than you and me. On the other side we have for example rattlesnakes which have some form of infrared eyes which can see the prey at night.

(C) Tetrachromacy

If you believe it or not but not only animals are tetrachomats but also humans can have four different color receptors!

Studies have shown that women who carry the color vision defective gene, can develop four different receptors in the eye and therefore have a broader color spectrum than the rest of us. This is a very rarely diagnosed phenomenon but definitely makes all of us colorblind compared to tetrachomatic women.

(D) Small-Field Tritanopia

And if you think the three points above don’t really prove that we are all colorblind this last point will definitely change your mind.

Normal color vision means you have three different color receptors: one peeking at red (L-cones), one at green (M-cones) and one at blue (S-cones). Together we have about 4.5 million of those receptors distributed all over our retina. Most of them are L- and M-cones and only about 7% are blue sensitive.

A closer look at the distribution of the color receptors shows, that in the very center of the retina, inside the fovea, there are no blue cones at all! As this spot is very small—you can think of visual field the size of a tennis ball at the other side of the court—this is called small-field tritanopia. See also my article about tritanopia to learn more about this type of color vision deficiency.

So in the center of our visual field we have no S-cones. This means only L- and M-cones can give us information about the colors in that spot and therefore we are all dichromats in the fovea. — And why do you don’t know anything about your central color blindness? Because your eyes don’t really focus on such a little point but often move around. This makes you believe, that you have trichromatic color vision over your whole visual field.

And because small-field tritanopia is true for all of us, everybody is at least a little bit colorblind! quod erat demonstrandum.