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Here is some information from several sources: The first section is from the Brain Games Program. There is video and written information on the page/link below if you click and view the first video and read next set of information on the page. This is in an easy to understand format.

Keep in mind that - Light/brightness is color. Color is light/brightness. Brightness and color perception is due to the variation of electromagnetic waves in the form of "invisible" unperceived radiation. ~~~~~~

From the National Geographic "Brain Games" TV program:
Think you understand the colors you see every day? Think an apple is actually red, or a leaf is really green? Think again. This episode of Brain Games puts your brain to the ultimate test with a series of interactive games and fascinating experiments that will REVEAL A SHOCKING TRUTH - COLOR IS JUST AN ILLUSION CREATED BY YOUR BRAIN. We'll show you how some colors can make you fly, reveal ghostly colors that don't actually exist, and if you play along you’ll see how color helps keep you alive.

In recent years, neuroscientists have used brain scans to investigate where and how color is perceived by the brain. A study published in 2010 in The Open Neuroimaging Journal suggests that it may be a pretty complex process that takes place in several areas, including a region of the visual cortex known as the fusiform gyrus, or V4.

"Color amounts to a beautiful illusion"

The Science of Color:

Primates, including humans, have pretty good color vision compared to a lot of other animals, which probably gave us and our hairier cousins an evolutionary advantage in hunting and in finding wild fruit and other plant-based food. But whether we're looking at blueberries or at a painting from Pablo Picasso's "Blue Period" in a museum, WHAT WE ACTUALLY PERCEIVE IS ELECTROMAGNETIC ENERGY, emitted by a source such as the Sun or an electric light fixture, and then reflected off other objects in the environment. But we can't see all the energy that's bouncing around in our environment. Visible light amounts to only a narrow swath in the middle of the electromagnetic spectrum—frequencies between 400 and 700 nanometers. "At the most basic level color is light and light consists of electromagnetic waves," explains Yale University.

http://bg3.nationalgeographic.com/episode/1/

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Here it from a physicist. Color is 100% a creation of your mind. This video is a nice easy to understand format.

This Is Physics Channel: Color only exists in your brain:
https://www.youtube.com/watch?v=fQczp0wtZQQ

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Researchers have studied vision more thoroughly than the other senses. Because people need sight to perform most daily activities, the sense of sight has evolved to be highly sophisticated. Vision, however, would not exist without the presence of light. Light is electromagnetic radiation that travels in the form of waves. Light is emitted from the sun, stars, fire, and light bulbs. Most other objects just reflect light.

People experience light as having three features: color, brightness, and saturation. These three types of experiences come from three corresponding characteristics of light waves:

•The color or hue of light depends on its wavelength, the distance between the peaks of its waves.
•The brightness of light is related to intensity or the amount of light an object emits or reflects. Brightness depends on light wave amplitude, the height of light waves. Brightness is also somewhat influenced by wavelength. Yellow light tends to look brighter than reds or blues.
•Saturation or colorfulness depends on light complexity, the range of wavelengths in light. The color of a single wavelength is pure spectral color. Such lights are called fully saturated. Outside a laboratory, light is rarely pure or of a single wavelength. Light is usually a mixture of several different wavelengths. The greater number of spectral colors in a light, the lower the saturation. Light of mixed wavelengths looks duller or paler than pure light.

In the universe | In your mind
Wavelength ——> Color
Amplitude ——> Brightness
Complexity ——> Saturation

http://www.sparknotes.com/psychology/psych101/sensation/section2.rhtml

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Visual Processing in the Brain:

After being processed in the thalamus and different areas of the brain, visual signals eventually reach the primary visual cortex in the occipital lobe of the brain’s cerebrum. In the 1960s, David Hubel and Torsten Wiesel demonstrated that highly specialized cells called feature detectors respond to these visual signals in the primary visual cortex. Feature detectors are neurons that respond to specific features of the environment, such as lines and edges.

From the visual cortex, visual signals often travel on to other parts of the brain, where more processing occurs. Cells deeper down the visual processing pathway are even more specialized than those in the visual cortex. Psychologists theorize that perception occurs when a large number of neurons in different parts of the brain activate. These neurons may respond to various features of the perceived object such as edges, angles, shapes, movement, brightness, and texture.

Color Vision

Objects in the world seem to be brightly colored, but they actually have no color at all. Red cars, green leaves, and blue sweaters certainly exist—but their color is a psychological experience. Objects only produce or reflect light of different wavelengths and amplitudes. Our eyes and brains then convert this light information to experiences of color. Color vision happens because of two different processes, which occur in sequence:
•The first process occurs in the retina and is explained by the trichromatic theory.
•The second process occurs in retinal ganglion cells and in cells in the thalamus and visual cortex. The opponent process theory explains this process.

These two theories are explained below.
http://www.sparknotes.com/psychology/psych101/sensation/section2/page/3/

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