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Comment by TheSpiceIsLife | Hacker News Reader

Google 'tetrachromacy test', first hit http://www.blogadilla.com/2008/06/08/are-you-a-tetrachromat/

that claim is quite dubious. I don't think it's possible to create metamers for people with normal 3-color vision on an RGB monitor. To do that you need an extra degree of freedom.

https://en.wikipedia.org/wiki/Metamerism_(color)

Hmm... I'm not sure about that. It's an interesting question. It's equivalent to the question: can we create two images on a computer monitor that appear the same to a person with normal color vision yet appear different to a colorblind person?

I think it would depend on the particular mapping from 3 to 2 dimensions... it might be possible.

> can we create two images on a computer monitor that appear the same to a person with normal color vision yet appear different to a colorblind person?

It surely depends on the type of colorblindness, there are many [1].

[1] http://en.wikipedia.org/wiki/Color_blindness

If you're monochromate or dichromate, I doubt that this is possible. Monochromates or dichromates are simply missing one or two color components out of three.

If you have anomalous trichromacy, you can by creating a monitor with pixels of different colors.

In any case, I don't see how it is possible to identify a tetrachromate with a trichromate (RGB) monitor. I tried to increase the contrast and change the hue of the color test to understand what was different between the apparently similar colors but I wasn't able to find any difference.

Using JPEG for a color test doesn't seem well thought out. Using GIMP (Colors, Map, Rotate Colors), one can make a letter appear in the center circle. I guess if the other circles had any letters in them, the compression ruined it.

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