1. A terminal device comprising: a priority storing unit for storing a range of natural colors which are in the natural world as a reference color area; a user interface (UI) generating unit for generating a UI window comprising an image indicating window to indicate an image from a user and to receive a command for correcting the image; a color editing unit for correcting natural color image data corresponding to the range of natural colors of the image in response to the command; and a controlling unit for controlling the UI generating unit to display whether or not the natural color image data are included in the reference color data area in the image indicating window by masking the natural color area determining whether the reference color data area comprises the natural color image data corrected by the color editing unit in real time.