How to convert image into overlapping blocks?

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h612
h612 on 5 Apr 2017
Edited: h612 on 6 Apr 2017
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

Answers (1)

Image Analyst
Image Analyst on 5 Apr 2017
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?
  1 Comment
h612
h612 on 6 Apr 2017
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 ])

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