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how I can measure the robustness of watermark?

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Eliza
Eliza 2017-12-10
编辑： Walter Roberson 2018-1-20
I am working on one of the watermarking algorithm, I wanna measure the robustness of the watermark Image the PNSR used for original Image , I could not use it for watermark because it is double Image , the measure should done between the Watermark and Extracted Watermark, all of images are unit8 class any suggestion please?
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Image Analyst
Image Analyst 2017-12-10
psnr() is a built-in function since R2014a. Why are you overwriting it with your own?
ALso, if you embedded a color watermark, and you're extracting a grayscale version of it, then your extraction method is not right. You should be able to extract the very same image you embedded.
Eliza
Eliza 2017-12-12
I used it but if it gives me negative value what does it mean?

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回答（1 个）

Walter Roberson
Walter Roberson 2017-12-10
double() the image that is uint8 before calculating the PSNR against the double() array.
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Eliza
Eliza 2017-12-10
the error in the dimension between the Original WM and Extracted WM
Subhadeep Koley
Subhadeep Koley 2018-1-20
编辑：Walter Roberson 2018-1-20
[row col]=size(original_wm);
extracted_wm=imresize(extracted_wm,[row,col]);
after executing this piece of code psnr() will work fine.
Apart from psnr you can also test structural symmetry between two images by calling
ssimval=ssim(extracted,original);
Hope this helps :)

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