Image processing apparatus and method, program, and storage medium

摘要

An image processing apparatus and method can perform gradation conversion of an image in which flatness of a pixel-value histogram of an image after gradation conversion is excellent, while using a specific gradation conversion function. A gradation conversion function represented using variables for specifying a gradation conversion characteristic is used. The values of the variables are determined based on flatness of a pixel-value histogram of an image obtained by converting an object image with the gradation conversion function. The object image is subjected to gradation conversion with the gradation conversion function determined by the determined values of the variables.