How to find centralized sub image from an image?

I have an image and divided into 2 * 2 grid. Now I want to get centralized sub-image of the same image so that I can find out the features of the centralized sub-image. How to do it?

[Guillaume]

What is a centralized subimage?

[anu]

Dotted one is a centralized image.

Answer 1

[Guillaume]

Isn't it simply:

centralised_subimage =  yourimage(end/4:3*end/4, end/4:3*end/4, :)