| 摘要 |
PROBLEM TO BE SOLVED: To prevent rising of a misidentification ratio due to a difference of magnifications, to reduce a processing load, to quickly carry out matching, and to accurately carry out matching even when an illuminance difference in sampling is large. SOLUTION: Two-dimensional discrete Fourier transform (DFT) is applied to image data R of a registered fingerprint and image data I of a matching fingerprint, to create registered Fourier image data R<SB>F</SB>and matching Fourier image data I<SB>F</SB>. Amplitude suppressing processing is applied to R<SB>F</SB>and IF to obtain R<SB>FL</SB>and I<SB>FL</SB>. Coordinate systems of R<SB>FL</SB>and I<SB>FL</SB>are converted into polar coordinate systems to obtain R<SB>PL</SB>and I<SB>PL</SB>. Distance suppressing processing is applied to R<SB>PL</SB>and I<SB>PL</SB>to obtain R<SB>PLL</SB>and I<SB>PLL</SB>. R<SB>PLL</SB>is matched (rough matching) with I<SB>PLL</SB>by an amplitude suppressing correlation method, magnification deviation between the two is determined from a position of a correlation peak obtained in the matching process, magnification deviation correction is carried out to the image data R of the registered fingerprint or the image data I of the matching fingerprint, and matching (accurate matching) is carried out by the amplitude suppressing correlation method. It can be applied to not only two dimensions such as fingerprints, but also to one-dimensional and three-dimensional patterns in the same way. COPYRIGHT: (C)2007,JPO&INPIT
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