How do divide a image into blocks and find the maximum value of each Block?

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S .p.aramesh S 2015-10-21

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https://ww2.mathworks.cn/matlabcentral/answers/250044-how-do-divide-a-image-into-blocks-and-find-the-maximum-value-of-each-block

回答： Image Analyst 2015-10-21

Actually i am doing ODBTC encoding for a color image.I do the RGB decomposition already.now i have to do divide a image into blocks and find the maximum value of each Block.Plz help me

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Answer 1

Walter Roberson 2015-10-21

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https://ww2.mathworks.cn/matlabcentral/answers/250044-how-do-divide-a-image-into-blocks-and-find-the-maximum-value-of-each-block#answer_196824

blockproc()

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S .p.aramesh S 2015-10-21

thank u for reply,it is correct or not

I = imread(file_name); maxfun = @(block_struct) max(block_struct.data);

block_size = [50 50]; block_max = blockproc(I,block_size,maxfun); disp(block_max); figure imshow(block_max); title('Block Processing - Simplest Syntax');

Stefan Raab 2015-10-21

在 MATLAB Online 中打开

The line

max(block_struct.data);

will return a vector of maximum values if the input is a matrix. If you want only the largest element, you have to use

max(block_struct.data(:));

Then the matrix is converted to a vector before the max value is extracted.

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Answer 2

Image Analyst 2015-10-21

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Walter and Stefan are correct. There is also some more complete code in the FAQ. I've also attached my two demos on blockproc(), for what it's worth. You can just modify it to take the max, like Stefan said.