Color curves
From The Glossary of Digital Photography
Also known as histograms. In Photoshop, selecting the curves function gives the photographer a choice of four or five different curves: the combination curve and one curve for each of the three colors in the case of RGB, or four colors in the case of CMYK. This choice allows the curves to make adjustments to any color or combination of colors. For example, if an RGB image is too red, selecting the red curve and pulling it down slightly will improve the image. See also RGB; CMYK
