What do those with color blindness, or more accurately, a color vision deficiency actually see? They see everything a normally sighted person might, just a little bit differently.
The principle measurement for vision deficiency is how clearly defined shapes appear to the eye. A person with color blindness can have 20/20 vision. The majority of color vision deficiencies take the form of not being able to distinguish one color from another or of seeing two different colors as the same color.
There are some cases of true color blindness. These persons can only see the world in black, gray and white. This is extremely rare and most of the time when someone is “color blind” they merely cannot see certain colors or certain colors transpose in their vision.
Color deficiency most commonly occurs in “the red/green spectrum”. A red/green color deficiency may be limited to certain shades of red or green or it may include all of them. This deficiency may be limited to either red or green. It may cause the eye to confuse red for green or vice versa. It may cause the eye to see shades of red or green that others cannot see, such as persistently reading beige as green. A red/green color deficiency can be very hard to deal with when driving at night and attempting to read a traffic light!
Color deficiency also happens commonly in “the yellow/blue spectrum”. Certain people may have issues with red, green, yellow and blue all together or in any variety of combinations.
No two people actually see color in the exact same way. Scientists who study vision believe that the number of colors an individual is able to appreciate is dependent upon the physical make-up of their eye. Inside of your eye are cones and color receptors; and these are as unique to you as your fingerprint is. Approximately 25% of all eyes use four cones while about 10% only use two. This indicates a broad spectrum of difference in vision from one person to the next.
There is no standard case of color blindness and a person with color deficiency is typically unaware that they are not seeing the world as others do. They only have their own eyes to rely on for perception and they are usually only aware of a discrepancy when someone chooses to argue with them about color.