发明申请
US20050129268A1 Method and system for watermarking an electrically depicted image
审中-公开
用于对电子描绘的图像进行水印的方法和系统
- 专利标题: Method and system for watermarking an electrically depicted image
- 专利标题(中): 用于对电子描绘的图像进行水印的方法和系统
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申请号: US10482073申请日: 2002-06-28
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公开(公告)号: US20050129268A1公开(公告)日: 2005-06-16
- 发明人: Kurato Maeno , Qibin Sun , Shih-Fu Chang , Masayuki Suto
- 申请人: Kurato Maeno , Qibin Sun , Shih-Fu Chang , Masayuki Suto
- 国际申请: PCT/US02/16599 WO 20020628
- 主分类号: G06K9/00
- IPC分类号: G06K9/00 ; G06T1/00 ; G09C1/00 ; H04N1/387
摘要:
A system for watermarking an image file selects coefficients using a selection procedure that is kept secret, and assigns the selected coefficients to coefficient pairs. The difference between the coefficients of the pairs is biased by a value that varies, preferably in a pseudo-random manner, and the biased differences are used to generate signature bits that characterize the authentic image at different locations. To detect an unauthorized alteration after the image file has been watermarked, coefficient pairs are selected using the same secret procedure that was originally used to generate the signature bits. The difference between the coefficients of the pairs is then biased and checked against the signature bits. Using a varying bias value permits a tolerance band for reducing false alarms to be used without the risk that would otherwise exist that evidence of an attack on the original image might be hidden in the tolerance band.