IMAGE PROCESSING DEVICE, IMAGE PROCESSING METHOD, IMAGE PROCESSING PROGRAM, AND RECORDING MEDIUM, EACH CAPABLE OF CORRECTING LUMINANCE OF IMAGE SO THAT THE LOCAL DETERIORATION OF GREY SCALES IS UNLIKELY TO OCCUR

An image processing device (100) includes: a luminance distribution information preparation section (110) for preparing a luminance histogram in which each luminance range serves as a class, by counting the number of pixels belonging to each luminance range; a weight correction section (120) for generating, for each luminance range, a weighting value which is proportional to a corresponding class value; and an image processing section (140) for correcting a luminance value of each pixel so that a difference between a maximum luminance value and a minimum luminance value in the luminance range is determined by an increasing function with respect to both (i) a frequency of the luminance range and (ii) a weighting value of the luminance range.