1. An imaging and display apparatus comprising: an imaging-and-display panel having an image display function and an imaging function; a backlight; a processor; and a memory device storing instructions which when executed by the processor cause the processor to operate with the imaging-and-display panel to: (a) obtain a display-light-based image by imaging an object close to the imaging-and-display panel during a light-emission period when the backlight is turned on; (b) obtain a shadow image by imaging the object during a non-light-emission period when the backlight is turned off; (c) generate a difference image representing a difference between the display-light-based image and the shadow image; and (d) obtain information concerning at least one of a position, shape, and size of the object taking the shadow image and the difference image into account.