What filters to process

Hi, I'm new to matlab but not to coding. I want to code a deep learning algorithm and use it for anomaly detection..

First steps are to apply filters to the image and outline the anomaly as much as possible (if I understood it correctly).

I've tried a few that I have checked online to get familiarized with the software.

Can anyone hint me to what filters I should be looking to if I want the algorithm to detect what's inside the red circles (there are no red circles in the original image, of course).

What I have noticed so far is that light should be more even around the picture, I think.

Any help is appreciated.

Thank you