How to do correlation between two tiff image files?

Find the pixel-wise correlation between two tiff images and store it in a matrix?

Answer 1

[KALYAN ACHARJYA]

im1=imread('image1.tif');
im2=imread('image2.tif');
result=corr2(im1,im2); 

Note: If the input images are RGB, convert both images in gray and apply corr2.

Please ensure that both images having same size.

[Thara C.S]

ok, cant we get a graph of correlation in matlab?

the result is a value!

[KALYAN ACHARJYA]

Direct corelation gives a number, if you are looking for matrics, please look on Correlation coefficients

im1=double(rgb2gray(imread('21_training.tif')));
im2=double(rgb2gray(imread('25_training.tif')));
R=corrcoef(im1,im2)

R =
    1.0000    0.9419
    0.9419    1.0000

But I dont know wheather it serves the main objective of your problem or not?

You can find the corrcoef of single matrix, which returns a matrix of coefficients.

im1=double(gray_image);
R=corrcoef(im1)

[Thara C.S]

but,

i need a graphical representation of pixel wise correlation between two tiif images?

Answer 2

[Image Analyst]

Try xcorr2():

correlationImage = xcorr2(image1, image2);
imshow(correlationImage, []);

It will give an image of the spatial correlation of image1 with image2. From that you can get profiles if you want.

[Yunus Emre SARI]

the process is taking too long, what do you think is the reason

[Image Analyst]

Your images are probably too big. You might want to do it in the Fourier domain by multiplying their FT then inverse FT.

[Yunus Emre SARI]

How to print the resulting tif file into a folder

[Image Analyst]

You can use imwrite(). If correlationImage is double, then convert to uint8 and then call imwrite():

uint8Image = uint8(mat2gray(correlationImage));
imwrite(uint8Image, fileName);