Dam trochę cytatów z książki Bruce Fraser "Real World Camera Raw"

Shadows. The Shadows slider is the black clipping control. It works very like the black input slider in Photoshop's Levels, letting you darken the shadows to set the black level. But since the Shadows control operates on the linear-gamma data, small moves tend to make bigger changes than the black input slider in Levels.

Brightness. Unlike its image-destroying counterpart in Photoshop, Camera Raw's Brightness control is a non-linear adjustment that works very much like the gray input slider in Levels. It lets you redistribute the midtone values without clipping the highlights or shadows. Note, however, that when you raise Brightness to values greater than 100, you can drive 8-bit highlight values to 255, which looks a lot like highlight clipping, but if you check the 16-bit values after conversion, you'll probably find that they aren't clipped.

Contrast. The Contrast slider also differs from the Photoshop adjustment of the same name. While Photoshop's Contrast is a linear shift, Camera Raw's Contrast applies an S-curve to the data, leaving the extreme shadows and highlights alone. Increasing the Contrast value from the default setting of +25 lightens values above the midtones and darkens values below the midtones, while reducing the Contrast value from the default does the reverse. Note that the midpoint around which Contrast adds the S-Curve is determined by the Brightness value