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What Is Color Constancy?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 25 September 2014
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Color constancy is a part of the visual perception system which allows people to perceive color in a variety of conditions, and to see some consistency in the color. An apple which is red in the bright morning sunlight will also appear red under candlelight and in the late afternoon, when the wavelengths of the light available are actually very different. Likewise, if the apple is partially in the sun and partially in the shade, an observer will read the entire apple as red. This allows someone to recognize the apple even though the conditions have changed, with the eyes perceiving the color as relatively constant.

This system is part of a larger system of subjective constancy. Subjective constancy is used by the brain to help people perceive objects in changing situations. This ensures that they can recognize those objects, which assists with comprehension of the world and can also become important for safety. For example, the ability to recognize a specific shape might help someone avoid a hazard, and the ability to compensate for distance when viewing a scene can also be important. Subjective constancy also allows people to identify and link thematic elements, as seen when people recognize a work of art because it depicts a familiar scene.

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Color constancy uses the input from various cone cells in the retina. The cones are sensitized to varying wavelengths of light, and their collective data is processed by the brain to determine which colors someone is looking at. Colors can be influenced by which wavelengths of light are available, and by surrounding colors, which is why a color can look very different depending on what is placed next to it.

This aspect of the human color perception system was uncovered in the 1970s. It was actually a photographer who identified the color constancy phenomenon, perhaps because photography often requires a very high awareness of color and available light. Color constancy has since been studied extensively to learn more about how people see color, and how perception of color can be distorted.

Many examples used to demonstrate color constancy and the tricks which can be played with color use a grid known as a Mondrian. The grid consists of a series of squares, with the experimenter manipulating available light levels to see how people perceive the colors of the squares. An orange square, for example, may appear red in a different wavelength, and squares of the same color can appear different, depending on which colors are surrounding them.

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summertime
Post 4

I think because of the human brain's ability to have accurate color constancy in our vision this actually leads to humans taking for granted the different types of color that are available in the sky during different times of day. As a photographer, you will learn that you need to be able to look at the sky and understand what kind of light is available.

The color constancy illusion is a strong one and I think it goes to show you just how much are operating changes the vision that we have to, things like hallucinations, visual distortions and optic impairments are just some of the examples of how our brain can distort the way we see the world.

ronburg44
Post 3

I basically think it's amazing that the human mind is capable of looking at an object of the same color that is split between two different types of available light and can interpret that color coming off the different surfaces at the same object.

This shows you the power of the human brain and its ability to process color images that are coming into our eyes. Color perception is absolutely needed in life and those that suffer from color blindness have an automatic disadvantage in being able to discern objects properly.

GraniteChief
Post 2

@youbiKan, Is correct in his analysis of the inability for most cameras to be able to accurately detect color constancy like human eye and mind can. However, vision science as well as advancements in technology and color vision theory, manufacturers are closing in on the ability for a camera to accurately detect in automatic white balance.

Some manufacturers are a lot further ahead of the game in this market area however most consumers are satisfied with the automatic settings coming off campus these days.

youbiKan
Post 1

The concept of color constancy can be easily understood in terms of photography. Our eyes ability to see color constancy refers to the fact that cameras are unable to interpret different types of colors in different types of light. Because of this technological limitation, cameras must have a white balance setting that is selected appropriately for the type of light available in the situation in which you were photographing.

Color images created by digital cameras are very susceptible to color shifting and the inability for the camera to create accurate color analysis of the light that is entering into the lens and on the sensor. It is left to human ability to be able to understand color in order for color processing of digital images to be accurate.

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