Apple Color 1.5 - Manual (Page 221)

Of course, you also have the option to lower the contrast ratio of an image. This might
be done as an adjustment to change the apparent time of day (dulling shadows while
maintaining bright highlights for a noon-time look) or simply as a stylistic choice (lighter
shadows and dimmer highlights for a softer look).
What Exactly Is Image Detail?
Image detail is discussed frequently in this and other chapters, mainly within the context
of operations that enhance perceived detail, and those that result in the loss of image
detail. Simply put, image detail refers to the natural variation in tone, color, and contrast
between adjacent pixels.
Because they occur at the outer boundaries of the video signal, the shadows and
highlights of an image are most susceptible to a loss of image detail when you make
contrast adjustments. This results in the "flattening" of areas in the shadows or highlights
when larger and larger groups of pixels in the picture are set to the same value (0 in
the shadows and 100 in the highlights).
It's important to preserve a certain amount of image detail in order to maintain a natural
look to the image. On the other hand, there's no reason you can't discard a bit of image
detail to achieve looks such as slightly crushed blacks, or widely expanded contrast for
a "high-contrast look" with both crushed blacks and clipped whites. Just be aware of
what, exactly, is happening to the image when you make these kinds of adjustments.
221 Chapter 9 The Primary In Room