For Loop Problem error

img=imread('C:\Users\Shalaw\Downloads\gray.jpeg');

[n,m]=size(img);

part1=img(1:n/2,1:m/2);

part2=img(1:n/2,(m/2)+1:end);

part3=img(n/2+1:end,1:m/2);

part4=img(n/2+1:end,m/2+1:end);

for i=1:4

subplot(2,2,i);

imshow(part1); -----> I want to change 1 to i, but i cant please help.

end

[Stephen23]

Simply use a cell array with indexing:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

Putting numbers into variable names is a sign that you are doing something wrong. In most cases using indexing is simpler, neater, and much more efficient.

Answer 1

[Adam]

img=imread('C:\Users\Shalaw\Downloads\gray.jpeg');
[n,m]=size(img);

part{1}=img(1:n/2,1:m/2);
part{2}=img(1:n/2,(m/2)+1:end);
part{3}=img(n/2+1:end,1:m/2);
part{4}=img(n/2+1:end,m/2+1:end);

for i=1:4
    subplot(2,2,i);
   
    imshow(part{i});
end

[shalaw faraj]

very helpful thanks.

Answer 2

[Andrei Bobrov]

img=imread('C:\Users\Shalaw\Downloads\gray.jpeg');
[n,m]=size(img);
imgs = mat2cell(img,[n,n]/2,[m,m]/2)';
for ii = 1:4
    subplot(2,2,ii);
    imshow(imgs{ii});
end

[shalaw faraj]

your answre is greate, what about 4*4 and 8*8 and .... ?

very thanks.

[Andrei Bobrov]

k = 4;

[n,m]=size(img);
imgs = mat2cell(img, n/k*ones(1,k), m/k*ones(1,k))';
for ii = 1:k^2
    subplot(k,k,ii);
    imshow(imgs{ii});
end

[shalaw faraj]

I am very sorry, but I want to find (mean, max, min, std, entropy) for each block and using for but it is not working please help. thanks again.

img=imread('C:\Users\Shalaw\Downloads\gray.jpeg');

[n,m]=size(img);

part{1}=img(1:n/2,1:m/2);

part{2}=img(1:n/2,(m/2)+1:end);

part{3}=img(n/2+1:end,1:m/2);

part{4}=img(n/2+1:end,m/2+1:end);

for i=1:4

subplot(2,2,i);

imshow(part{i});

Xmean{i}=mean(part{i});

Xmax{i}=max(part{i});

Xmin{i}=min(part{i});

Xstd{i}=std(part{i});

Xentropy{i}=entropy(part{i});

end