Pattern/Template matching with different intensity level images

Hi everyone!

I am trying to conduct a pattern matching between two images, the main hinderance being that the two images are of different intensity levels. To be specific, the images correspond to a decaying fluorescence signal and captured at two different times, therefore the difference in intensity. These high and low-intensity images are on my Google drive since they are large (13 MB each) to be uploaded here:

https://drive.google.com/file/d/160601-c7lbZJVs2-iPeM51aUM_ySP1x5/view?usp=sharing

https://drive.google.com/file/d/1g51OGalp10EInHOrpvVrE3M1IxZDzKx3/view?usp=sharing

As you can see, there is a distinct pattern (a vortex) in the first (high-intensity) image (from x = 800 to x = 1200 and y = 600 to y = 800). Please use the command

imrect(gca, [800, 600, 400, 200]);

to see what I am implying. I want to locate this pattern in the second image. So far, I have tried using normxcorr2, xcorr2 and a couple of other codes on MATLAB file exchange portal, but I am not able to crack this nut.

Any help would be appreciated!

TA

Answer 1

[Prasad Parameswaran]

The issue may be solved using histogram equalization with function "histeq". Refer link for more information:

https://in.mathworks.com/help/images/histogram-equalization.html