AUTHENTICATION OBJECT IMAGE-PICKUP METHOD AND DEVICE THEREFOR

摘要

An iris image-pickup method capable of capturing an iris image focused on the iris by passing an image signal produced by picking up the iris through a high-pass filter (41L), and searching for the lens position at which the output of this high-pass filter (41L) has a peak value by the hill-climbing search method. If high-luminance components included in the image signal are more than a predetermined number, the peak position of the high-frequency component in the image signal passed through a narrow band high-pass filter (41H) passing only the high-frequency band out of the passband of the high-pass filter (41L) is sought over the entire predetermined area in place of search for the focusing position by the hill-climbing search, and this peak position is made an iris focusing position. An iris image which is focused on not the eyeglass but the iris and sharp and high in authentication correctness can be acquired thereby, and an image focused on the iris can be acquired even when an authentication object person wears eyeglasses.