An image processing device includes: an estimating module configured to estimate boundaries of blocks in an input image; a characteristic value calculating module configured to calculate a characteristic value of a subject pixel group having constituent pixels including a pixel in the frame and at least one pixel that is adjacent to the pixel by calculating a degree of pixel value dispersion between the constituent pixels of the subject pixel group if all the constituent pixels belong to the same block; an strength value calculating module configured to calculate, from the characteristic value, a strength value to be used in performing pixel value smoothing; and a smoothing module configured to perform the pixel value smoothing according to the strength value.