How to plot watermark detector response ???????

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mcc mscelec
mcc mscelec on 17 Mar 2012
Could anyone help me to plot the '*watermark detector response'* which shows the response of the watermark detector to 1000 randomly generated watermarks of which only one matches the watermark embedded.
Say I - original image; I'- watermarked image ;W - original watermark ; W*- extracted watermark ; And the similarity of the watermarks is found using the code given below:
function SIM=WM_detect(W',W)
SIM=sum(W'.*W)/sqrt(sum(W'.*W));
end
The plot should resemble like in the link given below: http://scien.stanford.edu/pages/labsite/2000/ee368/projects2000/project5/Tests%20and%20Results.htm {The last response plot(using spread spectrum) for rotated & cropped image. }
(or)
Hope to get a response as soon as possible
Thanks a lot.
  2 Comments
mcc mscelec
mcc mscelec on 17 Mar 2012
The last response plot(using spread spectrum) for rotated & cropped image.
Basically I want to plot a graph which shows the response of the watermark detector to 1000 randomly generated watermarks of which only one matches the watermark which i embedded.

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Answers (1)

mcc mscelec
mcc mscelec on 14 Apr 2012
Code for WATERMARK DETECTOR RESPONSE FUNCTION
function WM_plot(r,c,ext_wm,orig_wm)
for k=1:1000
wm=randn(r,c);%depending on the size of the watermark
wm=uint8(wm);%if necessary
store(k)=WM_detect(ext_wm,wm);%wrong watermarks
if k == 400
store(k)=WM_detect(ext_wm,orig_wm);%original watermark detection
end
end
figure(1),plot(1:k,[store]),ylabel('Watermark detector response'),xlabel('random watermarks');
hold on
%threshold calculation
[peak,ind]=sort(store,'descend');
threshold=peak(2)+(peak(2)*0.1);%T=second highest peak+10percentof the same
figure(1),plot(1:1000,[threshold],'red');
hold on
figure(1),plot(1:1000,peak(2),'green');
Regards, mcc :)

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