An image processing device includes a reduced-image creating portion, a reduced-retinex-image forming portion, a normalizing-parameter setting portion, and an original-image correcting portion. The reduced-retinex-image forming portion calculates reflectance of each pixel in a reduced image based both on a pixel value of a subject pixel in a reduced image and on a peripheral average luminance of the subject pixel, thereby forming a reduced retinex image that is configured of reflectance of each pixel in the reduced image. The normalizing-parameter setting portion obtains frequencies of the reflectance in the reduced retinex image and sets an upper limit and a lower limit for normalization. The original-image correcting portion includes a retinex-image forming portion, a first normalizing portion, and a first correcting portion. The retinex-image forming portion calculates reflectance of each pixel in the original image based both on a pixel value of a subject pixel in the original image and on a peripheral average luminance of the subject pixel. The first normalizing portion normalizes the reflectance of the original image based on the upper limit and the lower limit, thereby obtaining a normalized reflectance for each pixel in the original image. The first correcting portion corrects the original image based both on the normalized reflectance and on the pixel value for each pixel in the original image, thereby obtaining a corrected original image.