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1. a property of a surface or substance due to absorption of certain light rays and reflection of others within the range of wavelengths (roughly 370 to 760 nm) adequate to excite the retinal receptors.
2. radiant energy within the range of adequate chromatic stimuli of the retina, i.e., between the infrared and the ultraviolet.
3. a sensory impression of one of the rainbow hues.
primary c's a small number of fundamental colors. In visual science this refers to red, green, and blue, the colors specifically picked up by the retinal cones; mixtures of varying proportions of the primary colors will yield the 150 discriminable hues of normal human vision. In painting and printing, the primary colors are red, blue, and yellow.
color vision deficiency inability to distinguish between certain colors, popularly called “color blindness.” A complete deficiency (monochromatic vision), the total inability to see colors, is rare, affecting only one person in 300,000. Much more common are the various types of partial deficiency. The most common is red-green confusion (see deuteranopia and protanopia), which affects approximately 8 million people in the United States.

Color vision is a function of the cones in the retina of the eye, which are stimulated by light and transmit impulses to the brain. It is now thought that there are three types of cones, each type stimulated by one of the primary colors in light (red, green, and blue or violet). In red-green color vision deficiency, there is a deficiency of either red or green receptors, so that the two colors do not appear distinct from each other.

Color vision is usually tested by the ishihara test with a series of pseudoisochromatic charts or plates. (See Atlas 4, Part F.) These have a letter, number, or symbol printed in dots of one color in the midst of dots of gray or other colors. The normal person can see the symbol with no difficulty, but the person with color vision deficiency cannot distinguish it from the background.

Although color vision deficiency may occasionally result from injuries, diseases, or certain drugs, most cases are hereditary. It is usually inherited by males through the mother, who carries the trait from her father although she is not color deficient herself. In some cases, if the grandfather is color deficient and the mother carries the trait, a daughter may inherit color vision deficiency, but the ratio of men to women with inherited forms is about 20 to 1. There is no known cure for color vision deficiency.


1. That aspect of the appearance of objects and light sources that may be specified as to hue, lightness (brightness), and saturation.
2. That portion of the visible (370-760 nm) electromagnetic spectrum specified by wavelength, luminosity, and purity.


1. That aspect of the appearance of objects and light sources that may be specified as to hue, lightness (brightness), and saturation.
2. That portion of the visible (370-760 nm) electromagnetic spectrum specified as to wavelength, luminosity, and purity.
Synonym(s): colour.

Patient discussion about color

Q. Why is the color draining from my eyes?! When I was little I had rich shiny cobalt blue eyes! As I grew up they faded or just started to dim in color. Being partially blind you can see in my left eye the its a really light color and creamy instead of my deep blue color... Why does my eye color dim?! I didnt think going blind had anything to do with the color of my eyes changing... Or is it something else?! Please, and thank you!

A. depends on your blindness, if it is caused by your cornea changing (corneal opacity)- it'll change your eye color to a cloudy white. it can also be caused by cataract.
are those the reason of your blindness?

Q. If someone as alcoholism do there eyes change color? My husband says his work mate told him that if you’re an alcoholic your eyes can change color. As an example If you have blue eyes they become a darker blue because of something in your bloodstream?. I think my husband’s workmate is winding my husband up, or is he telling the truth?

A. That is an untruth. The color of the eyes in an alcoholic will not change color. The only thing in the eyes that will change color are the corneas (the whites of the eyes) they will turn yellow due to jaundice and probably cirrhosis of the liver. The skin will also turn yellow with the jaundice.

Q. What exactly is PPD? I heard it is a substance in hair color and that some women are allergic to it How can I know if I’m allergic to it?

A. That sounds nasty... so how can I know if i'm allergic to it or not?

More discussions about color
References in periodicals archive ?
Nothing changes a room faster than color. Especially during hard economic times with an unhealthy housing market.
Let S = {1, 2, 3, 4} be the color set and d be the dissimilarity measure defined as d (r, s) = [absolute value of r - s]
Meanwhile, HunterLab unveiled the ColorQuest OL spectrophotometer designed specifically for on-line color measurement of clear/translucent film and sheet.
Whereas the high-resolution color camera can possibly mistake brown boxboard for magazines with brown print, safe detection with a CMYK sensor is considerably more likely, as brown board is seldom printed using the costly four-color process.
Increasing the spacing between a grating's ripples shrinks the angular spread of colors, and decreasing the spacing increases the spread.
This brilliant color appears only because the leaves of some plants, including maples, actually produce new pigments, called anthocyanins.
Part of that word-association has to do with the fact that many white sexuality researchers are researching people of color. For example, Melendez says, most research being done today on people with HIV is done on people of color with HIV.
The deeper the navy color, the more authority it represents.
"Creo helps Xerox customers by providing a color print server that increases the productivity of the DocuColor 3535, making it a compelling offering for a wide range of light-production customers."
I use color to differentiate and identify each vegetable and to define the skin tones and clothing of the people.
There are many kinds of anthocyanins, and they can change color according to certain characteristics of the plant matrix in which they are found.
Silver with contrasting color "washes" will extend its reach, with gold tones found on higher level vehicles.