PURPOSE: To obtain a reference point by performing the artificial Fourier transform a detect the distribution state of picture elements within a small area after separating this small area, and therefore detecting roughtly a cetner point of the entire picture to scan the small area around the detected center point through comparison among areas.
CONSTITUTION: A fingerprint is detected by a fingerprint picture extracting mechanism 1, and the picture data supplied to a TV camera part 2 is binary coded by a binary coding part 3 to be temporarily stored to a memory 4. Then the binary coded data is converted through a small area of each part. Then a feature extracting part 6 obtains a power spectrum F(ω), and a CPU5 compares the power spectra to extract a center point of a small area. In this case, an artifical Fourier transform is employed. In case a center point exists, the power spectrum F(ω) corresponding to the frequency ω corresponding to the cycle of a picture which is expanded radially has its peak value. Based on this peak value, the center point of a small area having the maximum power spectrum is decided as the center point of the fingerprint picture.
HASE MASAHIKO
HOSHINO HIROYUKI
SHIMIZU AKIHIRO
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