| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device, with which the truth/false of paper sheets can be highly accurately identified by optically detecting printed picture patterns on the paper sheets. SOLUTION: Concerning the method for detecting the optical features of paper sheets and identifying the truth/false of the paper sheets from this detected result, a prescribed position on the surface of the paper sheets is irradiated with the light of at least two mutually different wavelengths, at least one of color coefficient, lightness and chromaticity of the light transmitted through the paper sheets or reflected on the surface of the paper sheets for each of wavelengths is detected, the ratio of at least one of color coefficient, lightness and chromaticity of light for each of wavelengths is obtained and the truth/false of the paper sheets is identified corresponding to whether this ratio exceeds a reference value or not.
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