But I can't tell until far too late if I'm getting red - or if she is. If I can tell it's red, by that time it's fire engine red and a painful sunburn is already present. Test strips for hard water, pH, swimming pools, etc. When cooking, red deficient individuals cannot tell whether their piece of meat is raw or well done. Many can not tell the difference between green and ripe tomatoes or between ketchup and chocolate syrup.
Some food can even look definitely disgusting to color deficient individuals.
For example, people with a green deficiency cannot possibly eat spinach which to them just look like cow pat. They can however distinguish some citrus fruits. Oranges seem to be of a brighter yellow than that of lemons. Many color blind people cannot tell whether a woman is wearing lipstick or not. Disturbances of color vision will occur if the amount of pigment per cone is reduced or if one or more of the three cone systems are absent.