[WM]: PSNR of asynchrones attacks

[seddik hassene <seddik_hassene@yahoo.fr>]

Hello for all watermarkers.
   
  Yam seddik hassene, I work on image watermarking, please can any one help me by explaining me this problem:
   
  Once the image is watermarked and the watermark is embedded, I compute the PSNR for distortion mesures.
  After attacking the watermarked image by some asynchrones attacks (like geometric attacks) I find that the PSNR of the attacked
image increases when compared with the non attacked watermarked image instead of decreasing.
   
  In some papers I found that for asynchrones attacks they put UV that means unavalable, wheras for other papers they put a wright
PSNR value that decreases after asynchrones attacks.
  Please can anyone help me and explain me this matter.

		


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