1. A digital image processing apparatus comprising: a storage unit in which reference subject distance information used to perform out-of-focus image processing according to reference zoom information is stored; a zoom information obtaining unit configured to obtain zoom information; a reference subject distance information obtaining unit configured to obtain the reference subject distance information corresponding to the zoom information from the storage unit; a notification unit configured to output notification information corresponding to the reference subject distance information; an image generating unit configured to generate a first image in which a subject is focused, a second image in which a background is focused, and a third image that is not focused; a setting unit configured to set a subject region and a background region of each of the first image and the second image; and an out-of-focus image generating unit configured to generate an out-of-focus image by combining the subject region of the first image with the background region of the third image.