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

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)

<http://www.google.co.in/imgres?q=watermark+detection+matlab&hl=en&biw=1440&bih=785&gbv=2&tbm=isch&tbnid=93CLJJA1fj2TXM:&imgrefurl=http://nalag.cs.kuleuven.be/research/software/FRFT/&docid=LwQRVSfuQtpaZM&imgurl=http://nalag.cs.kuleuven.be/research/software/FRFT/fw3a.jpg&w=560&h=420&ei=JrNlT4qdH8n5rAfL89C8Bw&zoom=1>

Hope to get a response as soon as possible

Thanks a lot.

[Walter Roberson]

Which plot there? There are a number, and none of them are clear matches for what you seem to be asking to plot.

[mcc mscelec]

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.

Answer 1

[mcc mscelec]

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 :)