How to convert image into overlapping blocks?

I'm trying to extract overlapping patches (size of patch 257x257) of an image with a 50% overlap. I wrote this code. Not sure what went wrong>

a = i

mread('...');
[row col]=size(a)
for i=1:256:col-123
  for  j = 1:256:row-123
       if j~=1&&i~=1
           block=a(j-123:j+123,i-123:i+123)    
       else
           block=a(j:j+123,i:i+123)
       end
       imshow(block)
    end
end

Answer 1

[Image Analyst]

Assuming you got the 50% overlapping blocks, I'm not sure what you want to do with them. Why not just use blockproc() where you can specify a jumpsize of less than the window size to get overlapping?

[h612]

I've already tried with blockproc.

• However, it doesn't add neighboring pixels as it is, instead add an overlap of 0s on the boundry- of the full image.
• Also the resulting blocks that arent 257x257, it doesn't interpolate them etc to make it 257x257.

Here is what I tried

    function cropSaveBlock(bs)  
     subBlockRegion =(bs.data(:,:));
     fileName = [strrep(num2str(bs.location),' ','_') '.jpg'];
     imwrite(subBlockRegion, fileName);
     end
        a = imread('cameraman.tif');
        aa=blockproc(a, [257 257], @(bs)cropSaveBlock(bs.data),'BorderSize', [1 1 ])
      % aa=blockproc(a, [257 257], @(bs)cropSaveBlock(bs),'BorderSize', [123 123 ])