In one aspect of the invention, in image processing on contrast, an image
is divided into rectangles, and a histogram of value data of the image is
generated for each of the rectangles. It is discriminated whether the
histogram generated by said histogram generator has a plurality of peaks.
Then, contrast is enhanced in the unit of rectangle according to
histogram. When the histogram of the rectangle is discriminated to have a
plurality of peaks, a rectangle is divided into sub-areas and contrast is
enhanced in the rectangle in the unit of sub-area. Alternatively, the
contrast enhanced above is suppressed in the unit of rectangle on a
rectangle on which the histogram thereof is discriminated to have a
plurality of peaks.
