An image processing device includes a code detection unit configured to detect a code image included in the input image, a pixel value determination unit configured to determine whether a pixel value of each pixel included in the code image corresponds to an intermediate color between a color of code elements constituting the code image and a color of a space between the code elements, and a pixel value converting unit configured to convert a pixel value of a separated pixel that is separated from the code elements by k pixels or more, among intermediate color pixels that are pixels determined to correspond to the intermediate color, into a pixel value brighter than the intermediate color, wherein k is an integer of 2 or greater.