1. A subtractive color method comprising: obtaining a most used color that is a most popularly used color in an image; extracting small pixel groups from among pixel groups formed of continued pixels having an identical color other than the most used color in the image, the small pixel groups having a color of which a color difference with respect to the most used color is smaller than a predetermined threshold value and having a size thereof that is smaller than a predetermined size; and generating a resultant image resulted from applying the most used color to portions corresponding to the small pixel groups in the image.