Understanding Color Channels - Digital Camera Lessons
By Gene Rodman
Sometimes I need to hear the same thing told five times or more by different people before something sinks in. I remember having a difficult time understanding how the color photography thing ever happened. This is a perfect example of not knowing the technology but still being able to use it. Now my simple mind can understand black and white photography because it is just varying degrees of white or lack of white made when light excites little granules of silver. I guess I could understand how there could be different dyes on film that responded to different colors of reflected light but how can a digital photograph be in color? I mean isn't a digital photograph just a bunch of 1's and 0's? How is it possible to get a colored 1 or 0?
It is a good thing that there are smarter people figuring these things out than me. Well, just like in film photography there are red, green, and blue dye couplers in the color film emulsion, there are red, green, and blue channels in digital photography. The digital sensor has an array of red, green, and blue specific sensors that record varying brightness of each color. Each different color is recorded on your memory card much like different colors are recorded on the dyes in the film emulsion.
So here's the kicker; each channel records a black and white image. Each channel only records if there is a certain intensity (tone) of light present. yes=1, no=0. Do this with every level of brightness of each color (red, green, and blue) and you have a color image made of 1's and 0's. Even on the most basic image there are 256 different levels of brightness that your sensor can record on each channel. Many cameras can record over 65,000 or more different levels of brightness per channel. That's a lot of information.
When each channel is isolated on your computer you can see that each channel is a black and white image. Each channel just records brightness. The black and white image looks different for each channel because each channel is recording a different color, either reds, greens, or blues. The color image is made by combining the varying degrees of brightness from each of the red, green, and blue channels and electronically projecting them on your review screen or computer monitor in the color they represent. It is mind boggling to understand that all this happens when you click the shutter. Click, there it is! Technology.
One of the biggest gripes about consumer level cameras is the lag time between pressing the shutter and the time when the picture is taken. Be patient, the camera is doing a whole lot of work with a whole lot of information.
So is it really necessary to even have a vague knowledge of this to take good pictures? Of course not. I don't think about this stuff while I'm shooting. But just like a carpenter has to know how to figure out how to cut a set of stairs even though he or she might only do it once in a while it's important to understand as much of the big picture as possible.
Gene Rodman is a life long photographer and owns Montana Photographic Arts Gallery and Studio. You can view his website at http://www.MTPhotoArts.com.
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