[WM]: About PSNR

[Hongyi Zheng <zhenthree1983@yahoo.com.cn>]

Dear Sir/Miss:
         I am sending an email for a question about the PSNR.My code is =
following:
       =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
       function ratio=3Dpsnr(x,y)=20
     % x:original image
     % y:watermarked image
     [m,n]=3Dsize(x);
     x=3Ddouble(x);
     A=3Dmax(max(x));
     Sum=3Dsum(sum((x-y).^2));
     ratio=3D10*log10(A^2*m*n/Sum);
       =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
  Use the method I got a good PSNR, but the difference between the =
original  image and watermarked image is a little obvious.I don,t
know where my method of PSNR calculation is correct or not.Please check =
for me.
  Thank you very much.
  =20

 	=09
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<div>Dear Sir/Miss:</div>  <div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; I =
am sending an email for a question about the PSNR.My code is
following:</div>  =
<div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D</div>  =
<div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;function
ratio=3Dpsnr(x,y) <BR>&nbsp;&nbsp;&nbsp;&nbsp; % x:original =
image<BR>&nbsp;&nbsp;&nbsp;&nbsp; % y:watermarked
image<BR>&nbsp;&nbsp;&nbsp;&nbsp; =
[m,n]=3Dsize(x);<BR>&nbsp;&nbsp;&nbsp;&nbsp; =
x=3Ddouble(x);<BR>&nbsp;&nbsp;&nbsp;&nbsp;
A=3Dmax(max(x));<BR>&nbsp;&nbsp;&nbsp;&nbsp; =
Sum=3Dsum(sum((x-y).^2));<BR>&nbsp;&nbsp;&nbsp;&nbsp; =
ratio=3D10*log10(A^2*m*n/Sum);</div>
<div>&nbsp;&nbsp;&nbsp;&nbsp; =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D<=
/div>  <div>Use the method I got a good PSNR, but the difference between =
the
original &nbsp;image and watermarked image is a little obvious.I don,t =
know where my method of PSNR calculation is correct or
not.Please check for me.</div>  <div>Thank you very much.</div>  =
<div>&nbsp;</div><p>&#32;
		<hr size=3D1><a href=3D"http://cn.mail.yahoo.com/" target=3Dblank> =
=D1=C5=BB=A2=C3=E2=B7=D1=D3=CA=CF=E4-3.5G=C8=DD=C1=BF=A3=AC20M=B8=BD=BC=FE=
</a>
--0-39332892-1181550468=3D:12404--


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