If there is a 512*512 image which has to be sampled into 16*16 image patches?how

If there is a 512*512 image which has to be sampled into 16*16 image patches,how can I do that?

[Walter Roberson]

How does this question differ from your earlier http://www.mathworks.co.uk/matlabcentral/answers/111016-how-to-chop-the-region-of-interest-of-segmented-image-to-patches-samll-region-say-16-16 ?

[hamed abdulaziz]

Sorry,I did not see your previous answer on my question ,I tried this :

I = imread('d:\3.bmp');

I=imresize(I,[512 512]);

patch_cell = mat2cell( 8*ones(1,size(I,1)/8), 8*ones(1,size(I,2)/8), size(I,3) );

but I have this error

Error using mat2cell (line 107) Input arguments, D1 through D2, must sum to each dimension of the input matrix size, [1 64].'

Error in patchs (line 6) patch_cell = mat2cell( 8*ones(1,size(I,1)/8), 8*ones(1,size(I,2)/8), size(I,3) );

[hamed abdulaziz]

Please could you guide me to correct these errors?

Answer 1

[Matt J]

Using MAT2TILES

 patches = mat2tiles(YourImage,[16,16]);

[hamed abdulaziz]

Thank you very much Mr.Matt J ,I downloaded the function outCell=mat2tiles(inArray,varargin)

from http://www.mathworks.com/matlabcentral/fileexchange/35085-split-nd-array-into-equal-sized-cells/content/mat2tiles.m ,I used it the I got 32x32 cell is it correct?

[Matt J]

Yes. that is correct.

[hamed abdulaziz]

How can I show the shapes of patches to see the them?

[Image Analyst]

The shapes are rectangles. Do you mean you want to see where the rectangles are, say in lines superimposed over the original image where the patches were extracted from? Or do you want to see every patch as a separate sub image like the FAQ does?

Answer 2

[Image Analyst]

There are nice demos for this in the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_split_an_image_into_non-overlapping_blocks.3F

It does it two different ways. One using mat2cell(), and one using just simple indexing. It's a full blown demo with sample images and display of each sub-image that it extracted so you can see what it did.

Answer 3

[Jan]

The easiest way would be to let two FOR loops crop the parts from the original array. The details depend on what you want as output.

[hamed abdulaziz]

Thank you Mr.Jan,I would like to use this code

patch_cell = mat2cell( 8*ones(1,size(I,1)/8), 8*ones(1,size(I,2)/8), size(I,3) );

but I got these error

Error using mat2cell (line 107) Input arguments, D1 through D2, must sum to each dimension of the input matrix size, [1 64].'

Error in patchs (line 6) patch_cell = mat2cell( 8*ones(1,size(I,1)/8), 8*ones(1,size(I,2)/8), size(I,3) );

Please could you guide me to correct it?

Answer 4

[Walter Roberson]

patch_cell = mat2cell( I, 16*ones(1,size(I,1)/16), 16*ones(1,size(I,2)/16), size(I,3) );