How do I calculate the vertical and horizontal correlation of pixels in an image using matlab?

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I want to calculate the correlation of pixels of an encrypted image (for a vertical and horizontal pair of pixels). i know about the corr and used it as
RHO = corr(X)

but it's giving correlation as a matrix of correlations (i think for each and every pixel, it is showing different correlation) but i want one correlation for the whole image to compare some encrypted images, encrypted by different algorithms.

What I have tried:

i tried -
RHO = corr(image)
and
corr2(image);
but it's not working.

Posted 11-Oct-17 2:11am

ritu shaktawat

Updated 16-Oct-17 6:51am

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RedDk · Answer 1 · 2017-10-11T08:45:00

Solution 1

My friend Ali B. says ... this way:

function r_xy=AdjancyCorrPixel( P )
x1 = double(P(:,1:end-1));
y1 = double(P(:,2:end));
randIndex1 = randperm(numel(x1));
randIndex1 = randIndex1(1:3000);
x = x1(randIndex1);
y = y1(randIndex1);
r_xy = corrcoef(x,y);
scatter(x,y);
xlabel('Pixel gray value on location (x,y)')
ylabel('Pixel gray value on location (x+1,y)')
end

(
copied & pasted from:
MATLAB Central[^]
)

Posted 11-Oct-17 8:45am

RedDk

Comments

Afzaal Ahmad Zeeshan 11-Oct-17 18:36pm

Who is Ali B? And what does the code do exactly?

Instead of copying and pasting someone else's work, just by calling them your friend, does not work. You should post these suggestions as comments instead of answers.

I did not, but someone will downvote your post and that is a bad impact on your contributions. :-)