1. An image processing apparatus comprising: a brightness component extraction unit adapted to extract a brightness component from image data; a scale conversion unit adapted to obtain a distribution of the brightness component on relatively large scale; a brightness component improvement unit adapted to improve the distribution of the brightness component of the image data by using the brightness component and an output of said scale conversion unit; and an image reproduction unit adapted to reproduce the image data by using an output of said brightness component improvement unit as a distribution of a brightness component of a new image, wherein said image processing apparatus further comprises a face detection unit adapted to detect a face area from the image data, and said brightness component improvement unit adjusts a degree of improvement by using a distribution of a brightness component of the face area being an output of said face detection unit.