If you’ve been learning about digital imaging, whether by shooting with a digital camera or by scanning your film images, you’ve probably come across the concept of 8-bit and 16-bit images. Support for 16-bit editing seems to be all the rage these days, especially since the release of Photoshop CS. Even the new Photoshop Elements version 3 supports many 16-bit operations. Given that 16-bit images are by definition twice as big as 8-bit ones, you may be wondering why anyone would even want them.
An 8-bit RGB (red, green and blue) image uses numbers from 0 to 255 to represent each constituent color, or “channel” in the image. Zero is the complete absence of that color while 255 represents the maximum amount of that color. Thus, a value of (255,0,0) represents pure red, (0,255,0) would be pure green, (0,0,0) and (255,255,255) would mean pure black and pure white respectively, and so on. Zero through 255 gives 256 total distinct values that each of these three channels can have. If you multiple 256 times 256 times 256, you get 16.7 million different combinations. That’s a lot of different colors, hues and shades.