Apple Color 1.0 - Manual (Page 157)

Chapter 8 Video Scopes 157
The Luma histogram can be very useful for quickly comparing the luma of two shots so
you can adjust their shadows, midtones, and highlights to match more closely. For
example, if you were matching a cutaway shot to the one shown above, you can tell
just by looking that the image below is underexposed, but the Histogram gives you a
reference for spotting how far.
The shape of the histogram is also good for determining the amount of contrast in an
image. A low-contrast image, such as the one shown above, has a concentrated clump
of values nearer to the center of the graph. By comparison, a high-contrast image has a
wider distribution of values across the entire width of the histogram.
3D Color Space Scope
This scope displays an analysis of the color in the image projected within a 3D area. You
can select one of four different color spaces with which to represent the color data.
RGB
The RGB color space distributes color in space within a cube that represents the total
range of color that can be displayed:
 Absolute black and white lie at two opposing diagonal corners of the cube, with the
center of the diagonal being the desaturated grayscale range from black to white.
 The three primary colors red, green, and blue lie at the three corners connected to
black.
 The three secondary colors yellow, cyan, and magenta, lie at the three corners
connected to white.