STARE AT THE TOP square for a minute or more. Do not move your head, and keep your eyes right in the middle of the square.
Slowly move your eyes to the square below.
Glorious, isn't it?
You are seeing some colors that are impossible to actually portray in the real world, other than transiently as you see here. These are called “imaginary colors”. You can't make paint that shows those colors, nor can you project a color of that light on a screen, nor show it on a computer monitor. A color meter does not measure these colors.
Here is the problem. The human eye has basically three classes of color sensors or cone cells, one generally sensitive to the red side of the color spectrum, another sensitive to blue on the other side of the spectrum, and green in the middle, along with green-blue sensitive rod cells that work most prominently in dim lighting. There are three color sensors, three only (although there may be some people — probably females only — who have four classes, and very many males, mostly, who have less than three).
There are some deep, rich red colors which do not stimulate either your green or blue cone cells. There are some deep, rich, dark violet colors which do not stimulate green or red. However, there are no green colors whatsoever which do not also stimulate your red or blue cells, or even both.
Human color vision as it is has the potential to see these supergreen colors, unadulterated with excess red or blue. The experiment above shows that you can actually see these Colors even if its just for a brief moment.
There are some wide-gamut color systems which represent colors that cannot exist even in our imaginations, like a scarlet black or deep blue white. As far as I know a true wide-gamut color system that includes supergreen as one of its primaries does not exist, but it would be useful if it did, since it would closely represent the entire human visual system, including our imagination, while excluding those colors which are impossible to even imagine.
Here are the most commonly used color systems:
sRGB: 35% of entire gamut
ColorMatch RGB: a bit larger than sRGB, slightly different primaries
Adobe RGB: 50.6%
Wide-Gamut RGB: 77.6%
CMYK: smaller than sRGB, but not complete overlap.
ProPhoto RGB: most of the visible color gamut, 13% of the colors are imaginary or impossible.
L*a*b* colorspace: 100% of visible colors, with lots of impossible colors.
The color revolution started in 1983, when a startling paper by Hewitt Crane, a leading visual scientist, and his colleague Thomas Piantanida appeared in the journal Science. Titled "On Seeing Reddish Green and Yellowish Blue," it argued that forbidden colors can be perceived. The researchers had created images in which red and green stripes (and, in separate images, blue and yellow stripes) ran adjacent to each other. They showed the images to dozens of volunteers, using an eye tracker to hold the images fixed relative to the viewers' eyes. This ensured that light from each color stripe always entered the same retinal cells; for example, some cells always received yellow light, while other cells simultaneously received only blue light.
The observers of this unusual visual stimulus reported seeing the borders between the stripes gradually disappear, and the colors seem to flood into each other. Amazingly, the image seemed to override their eyes' opponency mechanism, and they said they perceived colors they'd never seen before.[The Most Amazing Optical Illusions (and How They Work)]
Wherever in the image of red and green stripes the observers looked, the color they saw was "simultaneously red and green," Crane and Piantanida wrote in their paper. Furthermore, "some observers indicated that although they were aware that what they were viewing was a color (that is, the field was not achromatic), they were unable to name or describe the color. One of these observers was an artist with a large color vocabulary."
Similarly, when the experiment was repeated with the image of blue and yellow stripes, "observers reported seeing the field as simultaneously blue and yellow, regardless of where in the field they turned their attention."
My display is a world first and should be able to produce these impossible colors as well.