Image processing method for determining and setting an optimized windowing and/or dose control of a medical diagnostic device based on x-ray radiation. The digitized image consisting of a number of picture elements of an picture data matrix B originally created by an x-ray detector is processed. The object area is determined by forming an input picture data matrix B1, by forming an ROI picture data matrix B2, by analysis of the ROI picture data elements and by selection of the ROI picture data elements belonging to the object area, and in that the signals of the ROI picture data elements of the object area are evaluated.