The Curves tool provides a master curve, plus red, green, and blue curve controls with fixed-control-point editing. This lets you adjust shadow, midtone and highlight areas with a single, easy-to-use control.

Contrast: Adds to the “S” shape of the overall curve.

Shadows: Weighted to the lower half of the curve.

Midtones: Weighted to the midpoint of the curve.

Highlights: Weighted to the upper half of the curve.

RGB, Red, Green, Blue: Allows adjustment on individual color channels.

Gamma Space: The assumed gamma of the input media.