MATLAB: How to divide a bmp image into blocks

blockprocImage Processing Toolboxresize

I want to divide a bmp image to a 8*8 blocks. Is there any way out? 'resize' only resizes the image but does not divide the image into blocks. Also, when I read the image( using imread), it should give me a 8*8 matrix.

Best Answer

Assuming your image size is a multiple of 8:
img = imread('C:\somewhere\someimage.bmp');
numblockheight = size(img, 1) / 8;
numblockwidth = size(img, 2) / 8;
assert(all(mod([numblockwidth, numblockheight], 1) == 0), 'Image size is not a multiple of 8')
imageblocks = mat2cell(img, ones(1, numblockheight) * 8, ones(1, numblockwidth) * 8, size(img, 3))
And to save all these:
destinationfolder = 'C:\somewhere';
for col = 1:size(imageblocks, 2)
   for row = 1:size(imageblocks, 1)
      imwrite(imageblocks{row, col}, fullfile(destinationfolder, sprintf('block%03d_%03d.bmp', row, col)));
   end
end
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