To make an intuitive interface for curves for color correction, a particular color is selected, such as gray, and the effect of each curve on pixels of that color may be displayed as a background image for the curve. A background image also may indicate a color to which tones corresponding to a selected and manipulated point of a curve will be modified or corrected. An image representing a gradient from the color component, through gray, to a complement of the color component may be displayed in association with the displayed function curve to suggest a result of color correction to be applied to the input image by manipulation of the function curve. A background image may suggest to the user what will happen if a point on the curve is moved. For example, if a user takes a point on the green curve that is in the center of the display and moves it to the lower right, the resulting image will have a magenta tint. The background image for the curve for the green channel shows more magenta in the lower right. A user can determine from an image to be corrected and the background image of the curves both which curve to use and approximately which direction to manipulate the curve.