Apple Shake 4 - Manual (Page 666)

666 Chapter 23 Color Correction
You can control the range of the image that is considered to be in the shadows,
midtones, and highlights in the Range Curves subtab. This tab displays your final color
lookup operator as a curve, your mask ranges (to turn on the display, click the Ranges
button at the bottom), and controls for the center of the low and high curves. Also, you
can toggle the output from the Normal, corrected image to a display of the Low areas
boosted to 1 and all else black; the Mid areas boosted to 1 and all else black; or the
High areas boosted to 1 and all else black. A colored display is used, rather than a
display based on luminance, since different channels have different values. In the
following, the range viewer controls, with Low, Mid, and High, are selected.