SYSTEM FOR PREVENTING UNAUTHORIZED APPROPRIATION OF IMAGE DATA

摘要

PROBLEM TO BE SOLVED: To prevent unauthorized appropriation of digital image data without deteriorating image quality. SOLUTION: This system is provided with image data fetch means 6 that receives digital image data in which electronic watermark data are embeded, an electronic watermark data detection means 8 that detects electronic watermark data from image data received by the electronic watermark data fetch means 6. When the electronic watermark data detection means 8 detects electronic watermark data, an image data recording means 7 does not record image data received by the electronic watermark data fetch means 6 onto a recording medium 9 so as to prevent illegal copying. The electronic watermark data are calculated according to a predetermined equation as to, e.g. a frequency component of digital image data subject to discrete cosine transformation.