1. An image processing device comprising: a motion predicting unit configured to detect, from a criteria image and a reference image, a motion vector of each block in an image; a motion compensating unit configured to generate a motion-compensated image by performing motion compensation on the reference image, using the motion vector; a correction value calculating unit configured to calculate a correction value for correcting a pixel value of a current pixel in a current block in the motion-compensated image based on a boundary difference value between the criteria image and the motion-compensated image, the boundary difference value being a difference value with respect to a pixel value of a boundary pixel in a boundary portion adjacent to an adjacent block in the current block; and an adding unit configured to add the correction value to the pixel value of the current pixel in the motion-compensated image.