how to break an image into sub images

i have an image having pixels 512*512 . i want to break it in equal sub images (for eg like into images of 8*8) and want to apply a function (can be any) on each sub image ??

Answer 1

[José-Luis]

Google, as well as Matlab answers are your friends:

http://stackoverflow.com/questions/1637000/how-to-divide-an-image-into-blocks-in-matlab

Answer 2

[Zainab Ishfaq]

Height=8; width=8;
currentimage = imread('Image.png');
[r,c,~]=size( currentimage );
count=0;
for i=0:Height:r
count=count+1;
for j=0:width:c
if((i+Height)<r && (j+width)<c)
Image=imcrop( currentimage ,[(i+1) (j+1) Height width]);
imwrite(Image,horzcat(currentfilename, num2str(count),'.tif'));
end
end
end

[ahmad Al sarairah]

I have an image with (643x643) dimensions , and i need to split it horizontally and vertically into 100 sub images,so that each sub image is (64x64)pixels using matlab code .

The sub images are blocks with (64x64) pixels ,so the height and the width of each block is equal 64 .

i used this code , but i get only 10 sub images .

[shital shinde]

anyone please send me above code but using parallel concept. Means using parfor loop. Actually I am working for image denoising, I want to divide the image into blocks and then try to perofrm denoisinng it. Please help me.

[Walter Roberson]

Change

for i=0:Height:r
count=count+1;

to

parfor i=0:Height:r
count=i+1;

[shital shinde]

error- Undefined function or variable 'currentfilename'.

I got this error when I am trying to run it,

[Walter Roberson]

infilename = 'Image.png';

Height=8; width=8;
currentimage = imread(infilename);
[r,c,~]=size( currentimage );

[~, currentfilename, ~] = fileparts(infilename);

for i=0:Height:r
    ridx = floor(i/Height) + 1;
    for j=0:width:c
        cidx = floor(j/width) + 1;
        if((i+Height)<r && (j+width)<c)
            Image=imcrop( currentimage ,[(i+1) (j+1) Height width]);
            outfilename = sprintf('%s_%03d_%03d.tif', ridx, cidx)
            imwrite(Image, outfilename);
        end
    end
end

[shital shinde]

It again gives the error sir. I attached screenshot. I make some modifications, but it didn't work. please tell me .

[Walter Roberson]

            outfilename = sprintf('%s_%03d_%03d.tif', currentfilename, ridx, cidx)

[shital shinde]

Thanks sir. It work now. I have one question. Can we parallelize the above example using parallel computing toolbox.

[Walter Roberson]

Yes. Just change for i to parfor i

As we have advised you before, the result will almost certainly be notably slower than your current code. But I know from your previous questions that you feel inclined to do that testing yourself.

Answer 3

[image-pro]

i have an error please help

Error in p8 (line 11)

Image=imcrop(currentimage ,[(i+1) (j+1) Height width]);

[Walter Roberson]

what is the error message?