An apparatus for extracting image data of an object in an input image data. The apparatus includes a display device having a display screen for displaying a plurality of predetermined images; a display controller for controlling the display device to display one of the predetermined images; an imaging device for taking an image of an object placed before the display screen in order to generate an input image data; a controller for controlling the imaging device to take an image of the object and the display screen when the display device displays one of the predetermined images in cooperation with the display controller; and an extractor for extracting image data of the object by comparing the input image data generated by imaging device with data of the one of the plurality of the predetermined images.