1. An imaging and display apparatus comprising: an imaging-and-display panel having an image display function and an imaging function; generating means for generating a difference image representing a difference between a display-light-based image and a shadow image, the display-light-based image being obtained by the imaging-and-display panel by imaging an object close to the imaging-and-display panel using display light from the imaging-and-display panel, the shadow image being obtained by the imaging-and-display panel by imaging a shadow of the object; and image processing means for obtaining information concerning at least one of a position, shape, and size of the object taking the shadow image and the difference image into account.