1. A display apparatus to estimate a depth, the apparatus comprising: a display panel which includes a plurality of apertures to receive light input from an external object; a sensor panel to acquire a plurality of images by detecting lights transmitted from the display panel through the plurality of apertures; and a processor to generate at least one refocused image based on a disparity set in association with a plurality of image acquiring areas on the sensor panel, and to calculate a depth from the external object to the display panel, using the at least one refocused image.