Apparatus and an accompanying method, for generating a 'watermarked' image; for subsequently detecting that watermark in a test image; and the watermarked image so formed.

A reference image (81) is visually compared with a test image (80) using the display (64) of a personal computer (63).

For example, components in the test image and borders may be scaled to create an appropriate test image for any client device.

A test image is provided and projected onto the eigenvectors of each of the categories so as to reconstruct the test image with the eigenvectors (38).

An acquisition unit (74) acquires a test image (an image of the slit plate (5) imaged upon adjustment of the focal point diameter).

A test image (IT) is acquired for a face to be identified, and a best path through the average face model (MAv) is calculated, based on the test image (IT).

The test images taken, or parts thereof, are evaluated with respect to the characteristic information thereof, and the test image having the most characteristic information is selected as the reference image.