| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an electronic watermark detecting method and apparatus capable of more precisely detecting watermark information which has been weakened by attacks such as image segmentation or scaling without increase in computational complexity or a circuit scale. <P>SOLUTION: The electronic watermark detecting method comprises: an extracting unit 21 for extracting a specific frequency component signal in an input image signal; a first orthogonal transforming unit 22A for performing orthogonal transformation on the input image sinal for creating a first orthogonal transformation image signal; a second orthogonal transforming unit 22B for performing orthogonal transformation on the specific frequency component signal for creating a second orthogonal transformation image signal; a synthesizing unit 24 for synthesizing the first orthogonal transformation image signal and the second orthogonal transformation image signal for creating a synthesized image signal; a third orthogonal transforming unit 26 for performing orthogonal transformation on the synthesized image signal for creating a third orthogonal transformation image signal; an estimating unit 27 for estimating watermark information embedded in the input image signal by searching a peak appeared in the third orthogonal transformation image signal; and amplitude compressing units 23A, 23B, 25 for performing amplitude compression with compression characteristics varied, according to at least either magnitude of amplitude of a target signal or frequency thereof for obtaining a compression signal assuming at least either one of first and second orthogonal transformation image signals, and the synthesized image signal as the target signal of the compression. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
