1. An image processing device comprising: a focal pixel setting unit configured to set a focal pixel among a plurality of pixels in an original image that is represented by original image data; a near pixel setting unit configured to set a pixel near the focal pixel as a near pixel; a calculating unit configured to calculate a degree to which a luminance value of the focal pixel differs from a luminance value of the near pixel; a target pixel determining unit that is configured to determine the focal pixel as a target pixel when the degree is greater than a reference value; and an editing unit configured to generate edited image data by editing the original image data, the edited image data representing an edited image having a supplemental image superimposed on the original image, the supplemental image being superimposed on an area encompassing the target pixel.