1. An X-ray image processing apparatus comprising: a calculating unit adapted to calculate a noise amount of an X-ray receiving unit on the basis of a difference value of a plurality of dark images acquired at different timings by said X-ray receiving unit when no X-rays are irradiated; a changing unit adapted to change a predetermined parameter for processing an X-ray image acquired by said X-ray receiving unit when X-rays are irradiated, in order to prevent the noise amount from being superposed on the X-ray image; and an image processing unit adapted to perform image processing on the X-ray image on the basis of the parameter changed by said changing unit.