| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique which can identify not only the presence or absence of tampering but also a tampered position with a preset accuracy. <P>SOLUTION: A block division unit 402 divides image data into image data of a first unit having a predetermined number of pixels. A block coefficient calculation unit 403 calculates image data coefficients of the first unit by performing preset calculations using the divided image data of the first unit. A cell division unit 406 divides one of the image data of the first unit divided by the block division unit 402 into image data of the second unit each smaller than the first unit. Two of the image data coefficients of the first unit are selected and determined as a pair, and data indicating a magnitude relationship between the image data coefficients of the first unit is generated for one pair to generate first verification data. Two of the image data coefficients of the second unit at preset positions are selected, and data indicating a magnitude relationship between the image data coefficients of the second unit in the pair is generated to generate second verification data. <P>COPYRIGHT: (C)2011,JPO&INPIT |
