An image processing device includes: a terminal that receives an image signal for a display for displaying images in directions, the display including pixels having sub-pixels and a parallax optical element for directing light from each sub-pixel in a direction predetermined for each sub-pixel, the signal including a grayscale value of each sub-pixel; a memory that stores information indicating a defective sub-pixel displayed in a direction due to a defect of the parallax optical element; and a corrector that determines, using the grayscale value of a sub-pixel whose predetermined direction is another direction different from the predetermined direction of the defective sub-pixel, a grayscale value of the defective sub-pixel for the image displayed in the other direction, and outputs a corrected image signal including, as a grayscale value of the defective sub-pixel, the smaller of the grayscale value of the defective sub-pixel in the image signal and the determined value.