Patent attributes
A picture image input method includes inputting a picture image of an object as a picture image signal. A histogram of a frequency with respect to brightness information of the picture image signal is created. A first brightness is created, which is a maximum brightness value within a region not greater than a first frequency value on a low brightness side of a brightness value which is lower by the a preset amount than the maximum brightness value within the histogram. A brightness group on a low brightness side of the first brightness side in the histogram is detected. A substantially maximum brightness value in the brightness group is set as a highlight point of the object. A gradation conversion table is created, which converts gradations of the picture image signal on the basis of the highlight point.
