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Color Perception and White Balance.


by eduardoangel – July 23rd, 2009

by Eduardo Angel

Color is what happens when your eyes and brain perceive light. Light (and color) comes in two ways, reflective and transmissive. With the first one, white light is reflected off objects that absorb some of its wavelength. So, when we print an image, the colors we see are the leftovers of light after the paper and ink have absorbed certain wavelengths. If blue and red are absorbed, we end up seeing green. This is referred as the Subtractive Color Model.


On the other hand, transmissive light is when light passes through a medium, just like looking at slides or negatives on a light table or viewing at images a computer screen. This is referred as the Additive Color Model because Red, Green and Blue are added together to create the color you see.


If we are looking at an object under different lighting situations (sunlight, a candle, and a flashlight, for example) we always perceive that the object has the same color: a red apple always appears red. Our brains are so amazingly powerful that they instantly do all the adjustment for us, continually remapping the white balance so that things look the way they should. That’s not the case for digital cameras. Since (thankfully) the lack the human brain, it may register the red apple as having different shades of red or even different colors. This is called chromatic adaptation or color constancy. When the correction occurs in a camera it is referred to as “white balance.”

On a later post I’ll talk about white balance techniques and why the “Auto” feature is NOT the way to go when you want the outmost control over your color.

Categories: Ambient, Cameras, Displays, Education, Lighting, Perception, Vision, White Balance | Tags: , ,

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