| 摘要 |
A method and apparatus for comparing a sample of printed material, such as a bank note, with a standard original print by scanning the sample and the original to provide reflectance values of text in corresponding zones in a preselected group of zones of a pattern, common to both original and sample and produced by selecting reflectance values occurring in selected parts of selected lines of scan. The difference in reflectance values of the text in corresponding zones of the preselected group of zones is obtained and from these differences the relative position of the corresponding text is determined. The relative position of the text in the remaining corresponding zones is then determined by interpolating or extrapolating the values representing the relative positions of the text in the selected zones of the group and from the reflectance values obtained from scanning those other corresponding zones. Instead of simultaneously scanning both sample and original, the original may be scanned first and the reflectance values stored, and then the sample scanned, the differences being obtained from the reflectance values produced while scanning and the stored reflectance values of corresponding zones.
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