Technology for carrying out a luminance range expansion process is provided. In the technology, the luminance range expansion process is carried out in a manner appropriate to the luminance histogram of image data. Using the white peak value WP which represents the maximum value of luminance and the APL which represents the mean value thereof in the luminance histogram of image data, an expansion coefficient for use in the luminance range expansion process is derived by referring to an expansion coefficient lookup table 210. On the basis of the expansion coefficient, the luminance range expansion process is performed on the image data.