1. A graphical user interface for performing color correction, comprising: an interface that displays a plurality of user modifiable function curves, wherein each function curve is for a different color component and maps input values for the color component of a pixel on a first axis to output values for the color component for the pixel on a second axis, wherein each function curve is displayed on a different one of a plurality of background images, wherein the pixels of the background image for a function curve for a color component are the colors of output pixels having output values for the color component that correspond to an input value for the color component from an input pixel of a selected color; and a processor that processes modifications made to the function curve to define a color correction operation.