Impossible or forbidden colors are combinations of visible light frequencies that are invisible to the human eye under normal conditions.
Usually the colors we see have red, green, and blue color receptors. Any combination of retinal signals output from one place in one eye cannot be seen directly, but can be mixed in the visual cortex of the brain by mixing color signals from two eyes or more than a portion of color signals from the same eye Generated.
Examples of these colors are yellow-blue and red-green. These colors look similar to red and green, or yellow and blue.
However, in some cases, one can still see impossible colors, as shown in the figures we have shown. Try to look for 20 seconds on the cross in the middle of the green circle, then move your eyes to the same cross in the white square, and you will see a light pink circle.