We have developed a perfect erasing technology to erase an image printed on a sheet of paper, with decolorable toner. The decolorable toner has leuco dye colored with developer. Heating discolors the toner due to dissociation of the dye and the developer. A human cannot recognize an image subdivided into pieces and equal brightness image against the background. These facts are known to be an area effect and a Liebmann effect in perception psychology. The image eraser has an erasing process consists of rubbing, dust cleaning and heating. After the process, a trace of the original image, such as a character, cannot be recognized. This method has achieved both complete destruction of information and renewal of the printed paper. We revealed principal factors for the erasing quality and the optimum process conditions. We demonstrated a new concept.