MATLAB: Problm in imwriting a arrayimage

digital image processingimage analysisimage processingimage segmentation

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% code
folder='C:\Users\Public\Videos\Sample Videos\pro\images'; m=0; for k = 1:890 % Get the base file name. baseFileName = sprintf('img%d.jpg', k); % Combine it with the folder to get the full filename. fullFileName = fullfile(folder, baseFileName); % Read the image file into an array. imageArray = imread(fullFileName); a=imageArray; figure(1); imshow(a); title('color image'); c=rgb2gray(a); b=imresize(c, [512 512]); figure(2); imshow(b); title('original gray scale image'); n=512; k=1; for i=1:1:n for j=1:2:n if (j<=n-1) s(i,k)=(b(i,j)+b(i,j+1))/2; d(i,k)=b(i,j)-b(i,j+1); end k=k+1; end k=1; end for i=1:1:n for j=1:1:n/2 b(i,j)=s(i,j); b(i,j+n/2)=d(i,j); end end for j=1:1:n/2 for i=1:2:n if i<=n-1 s(k,j)=(b(i,j)+b(i+1,j))/2; d(k,j)=b(i,j)-b(i+1,j); end k=k+1; end k=1; end for i=1:1:n/2 for j=1:1:n/2 b(i,j)=s(i,j); b(i+n/2,j)=d(i,j); end end figure(3); imshow(b); title('image after one level of compression') for i=1:1:n/2 for j=1:2:n/2 if (j<=n/2-1) s(i,k)=(b(i,j)+b(i,j+1))/2; d(i,k)=b(i,j)-b(i,j+1); end k=k+1; end k=1; end for i=1:1:n/2 for j=1:1:n/4 b(i,j)=s(i,j); b(i,j+n/4)=d(i,j); end end for j=1:1:n/4 for i=1:2:n/2 if i<=n/2-1 s(k,j)=(b(i,j)+b(i+1,j))/2; d(k,j)=b(i,j)-b(i+1,j); end k=k+1; end k=1; end for i=1:1:n/4 for j=1:1:n/4 b(i,j)=s(i,j); b(i+n/4,j)=d(i,j); end end figure(4); imshow(b); title('image after two level of compression') for i=1:1:n/4 for j=1:2:n/4 if (j<=n/4-1) s(i,k)=(b(i,j)+b(i,j+1))/2; d(i,k)=b(i,j)-b(i,j+1); end k=k+1; end k=1; end for i=1:1:n/4 for j=1:1:n/8 b(i,j)=s(i,j); b(i,j+n/8)=d(i,j); end end for j=1:1:n/8 for i=1:2:n/4 if i<=n/4-1 s(k,j)=(b(i,j)+b(i+1,j)/2); d(k,j)=b(i,j)-b(i+1,j); end k=k+1; end k=1; end for i=1:1:n/8 for j=1:1:n/8 b (i, j)=s(i,j); b (i+n/8, j)=d(i,j); end end b=imcrop(b,[0 0 64 64]); m=k; figure (5); imshow(b); title('image after third level of compression') b=imresize(b, [3456 4608]); imshow(b); format = 'jpg'; str = ['C:\Users\Public\Videos\Sample Videos\pro\Newr\im' num2str(m) '.jpg'] ; imwrite(b,str,format) ; m=m+1; end
end

Best Answer

  • rohan - when you step through the attached code, does the following line get called 18 times (I'm guessing this is how many images you are reading in based on the first for loop):
    str = ['C:\Users\Public\Videos\Sample Videos\pro\Ne\im' num2str(m) '.jpg'] ;
    If this line is invoked for every iteration of k, is it distinct on each iteration? I'm guessing it isn't, and here is why. Your first for loop iterates as:
    for k = 1:18
    However, there are several instances in the code where you re-use k for other purposes, and set it to 1 and then iterate again:
    k=1;
    for i=1:1:n
    for j=1:2:n
    if (j<=n-1)
    s(i,k)=(b(i,j)+b(i,j+1))/2;
    d(i,k)=b(i,j)-b(i,j+1);
    end
    k=k+1;
    end
    k=1;
    end
    This happens a handful of times including near the end:
    for j=1:1:n/8
    for i=1:2:n/4
    if i<=n/4-1
    s(k,j)=(b(i,j)+b(i+1,j)/2);
    d(k,j)=b(i,j)-b(i+1,j);
    end
    k=k+1;
    end
    k=1;
    end
    % some stuff and then:
    b=imcrop(b,[0 0 64 64]);
    m=k;
    Note how k is reset to one after every completion of the inner for loop (on i). And then m is initialized to k…which means that m is always one and so probably im1.jpg is the only image ever being saved. (Is that correct?)
    To correct this, k should never be modified by any inner loop within the code, just choose some other name for this alternate looping/indexing variable.