1. A digital image processing apparatus comprising: a lens; a photographing device that obtains data of a through image from light which has passed through the lens; and a digital signal processor that: prior to receiving a shutter-release signal, sequentially performs a blurring treatment on the through image obtained from the photographing device, sequentially displays the blurred image and the through image to simulate an auto-focus, and upon receiving the shutter-release signal, stores an image on a storage medium.