RE: [WM]: Normalized Correlation

["Matthew Miller" <mlm@research.nj.nec.com>]

The normalized correlation between two vectors, A and B, is usually
calculated as

  NC = Sumi( A(i)*B(i) ) / Sqrt( Sumi( A(i)*A(i) ) * Sumi( B(i)*B(i) )
)

(of course, in the case of two images, you would replace the summations
over i with summations over i and j).

-- Matt



-----Original Message-----
From: watermarking-owner@watermarkingworld.org
[mailto:watermarking-owner@watermarkingworld.org]On Behalf Of storein
Sent: Tuesday, August 13, 2002 8:44 PM
To: <watermarking@watermarkingworld.org>
Subject: [WM]: Normalized Correlation


Hi everybody ,

          I want to compute the comparability of two bitmap
          I use NC coefficient (Normalized Correlation ) to

          the first Image  is W(i,j),the second image is W1(i,j)

              the fomula is :

                        NC=Sumi(Sumj(W(i,j)*W1(i,j)))
/Sumi(Sumj(W(i,j)*W(i,j)))

         but I find that the result is not reasonable .

         Such As if W(i,j) is  W(0,0)=255,W(0,1)=0,W(0,2)=0
                    W1(i,j) is W1(0,0)=255,W(0,1)=255,W(0,2)=255

         you will get NC=1;

         it is not reasonable .

         is there a good method of computeing the comparabilitybitmap
images??


        thank you very much .



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