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.
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].
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.
