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Monday, June 07, 2010
8-bit, 10-bit, 32-bit, and more
Karl Soule | 06/07
Understanding Color Processing in Adobe Premiere Pro
Recently, I’ve been getting a lot of questions about the new icons in the Premiere Pro Effects panel, in particular, the “32-Bit” icon seen at left.
People have asked how these effects relate to the 64-bit Mercury Engine, if they are limited in some way? The answer is no - these icons mean that these effects use 32-bit floating point color, the gold standard of color processing.
Trying to understand video color precision is, well, a confusing task. There are so many different terms floated around - 8-bit and 10-bit color are used to describe cameras, while software talks about 8 bits per channel, 16 bits per channel, and 32-bits per channel “floating point” color. What does it all mean? And, for the colorist, how does Premiere Pro handle color? If these are burning questions in your mind, then read on.
When your camera processes the light coming in the lens into data, it has to assign a number to each of the colors being recorded. Each pixel gets its own set of numbers. Typically a low number means very little of that color - a pixel with an RGB value of 0,0,0 would be completely black.
If 0,0,0 represents black, then what represents white? Well, that depends on what we call the bit depth. The higher the bit depth, the bigger each number can get.
Let’s look at one color - blue. In an 8-bit world, blue is represented by a number than can be between 0 and 255. If I had a knob to adjust the value of blue, it would look like this:

Pretend that this knob makes a “click” every time you raise or lower the value, and there are 256 distinct “clicks” on the knob. This means that there are 256 “steps” between the brightest, most saturated blue, and no blue at all. A “middle-of-the-road” value of blue would be around 128 on this scale. Adjustments have to be made in whole “clicks” - there is no value of “127.5” in 8-bit color precision.
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