An image processing device includes a judgement section and a generation section. A latent image, which would be retained or eliminated by photocopying, is to be superposed with machine-readable code images, which are encoded supplementary information, to generate a superposed image. The judgement section judges overlapping of the latent image with the machine-readable code images. The generation section, on the basis of judgement results from the judgement section, determines an arrangement of the machine-readable code images and generates the superposed image.