Extracting 20 patches from the image

i have images of size 256*130 each. I want to extract 20 patches from the center of the image so that patches only contain the brain part of the image not the black background.then i want to save those patches in separate folder. i have researched but google result is only for patching the whole image. i am attaching a sample image.

[Walter Roberson]

So after the ROI for the inside of the brain is created, it should be randomly divided into 20 non-overlapping sections? Do the patches need to be individually contiguous?

[prashant singh]

no,the patches can be random. They don't have to be contiguous. Also, the number of patches can be from 15 to 20. My major concern is to save the patches from the brain part of the image. the patches could of size 16*16 or 32*32.

[Image Analyst]

Who knows? How about qtdecomp() (quadtree decomposition)? Or a regular grid? Or circular/radial sectors?

[prashant singh]

I am not very familiar with the terms as i am a noob in image processing. It will be still very helpful if i can just take out 15 to 20 patches of size 32*32 from the center and save them. As i am low on time i can ignore the taking out patches from the brain part and could apply patching on whole image and want to save it.

[Image Analyst]

OK, let's try these terms: "Which ones?" "What patches?" "Where are they?"

Beyond that, what is the purpose of all this? Why get such patches in the first place? What good are they going to do you?