I want to divide an image into 25 equal tiles with the help of for loop...

I've done it with my basic knowledge but its very large code plz help me out to convert it into for loop my code is as follow,

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aj=imread('cameraman.tif'); %Image contains my real time edge detected picture but here taken Cameraman as an example
[h w]=size(aj)
wm=floor(w/5);
hm=floor(h/5);
figure;
aj1=aj(1:hm,1:wm,:);
subplot(5,5,1);imshow(aj1);
aj2=aj(1:hm,wm:2*wm,:);
subplot(5,5,2);imshow(aj2);
aj3=aj(1:hm,2*wm:3*wm,:);
subplot(5,5,3);imshow(aj3);
aj4=aj(1:hm,3*wm:4*wm,:);
subplot(5,5,4);imshow(aj4);
aj5=aj(1:hm,4*wm:5*wm,:);
subplot(5,5,5);imshow(aj5);
aj6=aj(hm:2*hm,1:wm,:);
subplot(5,5,6);imshow(aj6);
aj7=aj(hm:2*hm,wm:2*wm,:);
subplot(5,5,7);imshow(aj7);
aj8=aj(hm:2*hm,2*wm:3*wm,:);
subplot(5,5,8);imshow(aj8);
aj9=aj(hm:2*hm,3*wm:4*wm,:);
subplot(5,5,9);imshow(aj9);
aj10=aj(hm:2*hm,4*wm:5*wm,:);
subplot(5,5,10);imshow(aj10);
aj11=aj(2*hm:3*hm,1:wm,:);
subplot(5,5,11);imshow(aj11);
aj12=aj(2*hm:3*hm,wm:2*wm,:);
subplot(5,5,12);imshow(aj12);
aj13=aj(2*hm:3*hm,2*wm:3*wm,:);
subplot(5,5,13);imshow(aj13);
aj14=aj(2*hm:3*hm,3*wm:4*wm,:);
subplot(5,5,14);imshow(aj14);
aj15=aj(2*hm:3*hm,4*wm:5*wm,:);
subplot(5,5,15);imshow(aj15);
aj16=aj(3*hm:4*hm,1:wm,:);
subplot(5,5,16);imshow(aj16);
aj17=aj(3*hm:4*hm,wm:2*wm,:);
subplot(5,5,17);imshow(aj17);
aj18=aj(3*hm:4*hm,2*wm:3*wm,:);
subplot(5,5,18);imshow(aj18);
aj19=aj(3*hm:4*hm,3*wm:4*wm,:);
subplot(5,5,19);imshow(aj19);
aj20=aj(3*hm:4*hm,4*wm:5*wm,:);
subplot(5,5,20);imshow(aj20);
aj21=aj(4*hm:5*hm,1:wm,:);
subplot(5,5,21);imshow(aj21);
aj22=aj(4*hm:5*hm,wm:2*wm,:);
subplot(5,5,22);imshow(aj22);
aj23=aj(4*hm:5*hm,2*wm:3*wm,:);
subplot(5,5,23);imshow(aj23);
aj24=aj(4*hm:5*hm,3*wm:4*wm,:);
subplot(5,5,24);imshow(aj24);
aj25=aj(4*hm:5*hm,4*wm:5*wm,:);
subplot(5,5,25);imshow(aj25);

[Stephen23]

Tip: whenever you write repeating code then stop and use a better method:

• loops
• functions

Creating lots of numbered variables is a very bad sign, because beginners always want to access the variable names dynamically. Don't do this:

http://www.mathworks.com/matlabcentral/answers/196952-how-to-create-new-variables-in-batches-with-strcat

[Ajinkya Paikekari]

Hello stephen sir, Actually I want to divide image in small tiles and then need to count number of white pixels in each tile. I understand that it could be a lot easier with loops but i'm just trying n not getting outcomes , will u plz help me to do it?

[Image Analyst]

Aha, the real need is finally revealed! You don't need to split up the image into a bunch of separate images at all. You just need to use blockproc().

[Ajinkya Paikekari]

It will be really great if u show me how to use blockproc()

thank u!

[Matt J]

I think splitting into separate images will be faster than blockproc. However, see also my Answer using sepblockfun. That should be even faster.

Answer 1

[Matt J]

Consider using MAT2TILES ( Download ).

   ajTiles=mat2tiles(imread('cameraman.tif'),[hm,wm]+1).';

   for k=1:25

       subplot(5,5,k); imshow(ajTiles{k});

   end

[Ajinkya Paikekari]

this error is occurring sir

[Matt J]

Not for me. For me it runs fine.

Answer 2

[Image Analyst]

So, other than not knowing how to format your code, which can be solved with this link, what's the problem?

There is a FAQ on dividing an image up into tiles/blocks: http://matlab.wikia.com/wiki/FAQ#How_do_I_split_an_image_into_non-overlapping_blocks.3F

[Ajinkya Paikekari]

I have tried this sir bt the block sizes are not constant in this case

Answer 3

[Matt J]

Actually I want to divide image in small tiles and then need to count number of white pixels in each tile.

You may have to pad your image so that it divides evently into hm x wm blocks, but once you do, you can use SEPBLOCKFUN ( Download ) to efficiently count the number of white pixels per block. Example,

   blackwhite=rand(15)<.5; %Hypothetical black and white image

   counts3x3=sepblockfun(blackwhite ,[3,3],'sum'); 
                             %Number of white pixels per 3x3 block