| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for embedding additional information into a halftone image such that it can be detected surely even in an environment susceptible to noise incident to output from a printer. SOLUTION: A continuous tone image is inputted (S100) and a noise mask including additional information is created (S110). A threshold matrix is modulated based on that noise mask (S120). The continuous tone image is binarized using a modulated threshold matrix (S130). The noise mask can be made by performing image conversion of a noise image formed of noise signal by orthogonal function expansion, imparting additional information to a noise conversion image thus obtained and then performing reverse image conversion. A binarized image embedded with additional information can be detected by performing image conversion through orthogonal function conversion. COPYRIGHT: (C)2005,JPO&NCIPI
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