1. A photo-therapy method using a display device, the photo-therapy method comprising: providing a display device configured to display a normal image; receiving a viewing time input and a photo-therapy selection input, wherein the viewing time input represents an expected viewing time of a user and the photo-therapy selection input represents an expected viewing time of a user and the photo-therapy selection input represents a photo-therapy selected by the user; calculating a period of time for displaying a photo-therapy image based on the expected viewing time and a suggested treatment time of the selected photo-therapy; inserting the photo-therapy image into the normal image during the period of the photo-therapy image; and displaying image frames on the display device including the normal image interposed with the photo-therapy image, wherein the photo-therapy image includes at least a portion of color-amplified sub-pixels, and wherein an amplified color of the color-amplified sub-pixels is determined by the user's selection input for the photo-therapy.