Gradation attributes control according to characteristics of image

A gradation attributes correcting device to correct gradation attributes of an input image signal includes a brightness gradation correcting unit to correct gradation attributes with respect to brightness of an image indicated by the input image signal. The brightness gradation correcting unit includes a characteristic information acquisition unit, a correction information decision unit, and a brightness gradation processing unit. The characteristic information acquisition unit acquires a minimum, average, and maximum brightness, of an image on a frame from the input image signal. The correction information decision unit determines correction information to correct the gradation attributes with respect to brightness according to combinations of the acquired minimum, average and maximum brightness of the image on the frame. The brightness gradation correction processing unit establishes a polynomial function for the image on the frame based on the correction information to correct the gradation attributes by arithmetic operation using the polynomial function.