Patent ID: 8743186

Claim:
A depth expansion apparatus that can generate or display an image with an expanded depth of focus on the basis of a plurality of images in different focus positions, the depth expansion apparatus comprising: an image pickup optical system and an image pickup device configured to form and pick up a reference image (hereinafter referred to as image A) and an image in a focus position different from a focus position of the image A (hereinafter referred to as image B); and a depth-expanded-image forming section configured to generate or display, on the basis of a luminance change for each of corresponding pixels in the image A and the image B, a depth expanded image that maintains a relation between a distance from an object point to the image pickup optical system and luminance, wherein when an image side NA of the image A is represented as NA′, a lower one of resolution determined by the image pickup optical system and resolution determined by the image pickup device is represented as R, an optical path interval between a surface on which the image A is formed and a surface on which the image B is formed is represented as d, NA of an image at a near photographing distance among the image A and the image B is represented as NAn, and NA of an image at a far photographing distance among the image A and the image B is represented as NAf, the image pickup optical system and the image pickup device are configured to satisfy the following conditional expressions (1) and (2): R×NA′/ 2≦ d (1) 0.05≦( NAf/NAn ) 2 ≦0.9 (2).