An image processing device calculates a frequency of a pixel value for each block, generates a first histogram formed by N bins, mixes the first histogram of a high luminance block and the first histogram of each block, and thereby generates a second histogram for each block. Based on the second histograms of a block including a target pixel and an adjacent block, a frequency of a pixel value that depends on a pixel position in the block of the target pixel is calculated, and a third histogram is generated for each pixel. A relationship between the pixel value and an output value of the pixel value is generated based on the third histogram such that a maximum cumulative frequency of the third histogram matches a maximum value of the output value of the pixel value, and the output value is calculated from the pixel value of the target pixel.