How to divide an image into blocks in MATLAB?

Question

I have a 256x256 image and I want to divide it into 4 blocks of 128x128 each and address them as A1 to A4. Now I want to call them separately and do some operations on them.

Answer 1

Its it better for you to make your program work for all sizes of images not just for 256*256.

[row, col]=size(your_image);
mr = round(row/2); % median of rows
mc = round(col/2); % median of columns
% Now divide your image and call each of them separately and do what ever you   want
top_left  = your_image(1:mr  , 1:mc);
top_right = your_image(1:mr  , (mc+1):col); 
bot_left  = your_image((mr+1):row , 1:mc);
bot_right = your_image((mr+1):row , (mc+1):col);
% final stage is to combining these parts again to return to its original shape 
Back_to_original = [top_left,top_right ; bot_left,bot_right]; `   

hope this will be useful for you.