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Are there any colors that human beings can not see?
Question Date: 2010-12-06
Answer 1:

There are two parts to the answer, and the first one depends on what you call "colors". The colors of visible light, as spread out in the rainbow, are a section of the spectrum of electromagnetic radiation. Bordering this section are infrared and ultraviolet light, which are invisible to the human eye (yet some animals can detect these). Further "away", but also electromagnetic waves are e.g. X-rays on one end past the ultraviolet, and microwaves and radiowaves past the infrared. While all these are invisible to humans, one might not call them "colors" in the sense that color refers to something that one can see. So for this part, the answer is yes or no depending on what you would call colors.

Then there is "color blindness", which does not affect all human beings (so again, whether the answer is yes or no depends on what exactly your question is aimed at). The most well known kind of "color blindness" is red-green deficiency, which occurs, in case of Northern European ancestry, in about 8 percent of males and 0.5 percent of females (Deeb, S.S.; Clin. Genet. 67, 369377 (2005).). This is a genetic condition which individuals can have to a greater or lesser degree. In the extreme case, red and green (of similar brightness) look the same to these people, and may even appear as gray. For a person with normal vision, this is not so easy to imagine and to help with the design of images that work for all people, some graphics software offers color blindness proofing filters that simulate what an image will look like to individuals with color blindness and allow to adjust the image to make it universally accessible (for an example see, e.g., Adobe Photoshop accessibility overview at


The next website allows one to check one's own images online, without the need for commercial software such as Photoshop:


Answer 2:

Our eyes are sensitive to light which lies in a very small region of the electromagnetic spectrum labeled "visible light" (click on color-spectrum, below). This "visible light" corresponds to a wavelength range of 400 - 700 nanometers (nm) and a color range of violet through red. The human eye is not capable of "seeing" radiation with wavelengths outside the visible spectrum. The visible colors from shortest to longest wavelength are: violet, blue, green, yellow, orange, and red.

Ultraviolet radiation has a shorter wavelength than the visible violet light. This energy with wavelengths too short to see is "bluer than blue". Infrared radiation has a longer wavelength than visible red light. Energy whose wavelength is too long to see is "redder than red". The term "Infra-" means "lower than".White light is a mixture of the colors of the visible spectrum. Black is a total absence of light.

There are many wavelengths in the electromagnetic spectrum the human eye cannot detect. We can't see them because our eyes are not made to see them directly, insects can see other parts of the spectrum of light we can't. For example, bees and butterflies can see into the ultraviolet, and snakes can see/sense the infra-red that a small mouse emits in the night. We would need special cameras to see those frequencies.

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