Image processing apparatus and method for contrast enhancement by histogram equalization

摘要

Processing for improving the contrast of an image of interest is executed by an image processing circuit in an X-ray photography apparatus. The image is decomposed into coefficient values of a plurality of frequency bands by a frequency-component decomposition circuit to obtain coefficients of each and every frequency band. A coefficient conversion circuit converts coefficient values with regard to at least one frequency band of the plurality of frequency bands in such a manner that a frequency distribution of coefficient values of every frequency band will become a prescribed frequency distribution. A restoration circuit generates an image using the coefficient values obtained by the conversion performed by the coefficient conversion circuit.