Why I cant use the same for loop to interpolate the colomn? Only in row.

Question

Dingbang Liang 2018-5-29

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/402965-why-i-cant-use-the-same-for-loop-to-interpolate-the-colomn-only-in-row

编辑： Ameer Hamza 2018-5-29

Lena_half = imread('lena_half.tif');
Row = 512;   % interp1 along row
[m,n,p] = size(Lena_half);
Enlarge_lena = zeros(m, Row, p);
xi = linspace(1, n, Row);
for i = 1:n
    for j = 1:p
        Enlarged = interp1(1:n,double(Lena_half(i,:,j)),xi);
        Enlarge_lena(i,:,j) = Enlarged;
    end
end
Enlarge_lena = uint8(Enlarge_lena);
figure(1)
imshow(Enlarge_lena)
Col = 512;
[a,b,c] = size(Enlarge_lena);
Enlarge_lenaCol = zeros(Col, b, c);
yi = linspace(1, a, Col);
for d = 1:a
    for o = 1:c
        Enlagred_le = interp1(1:a,double(Enlarge_lena(o,:,d)),yi);
        Enlarge_lenaCol(o,:,d) = Enlarged_le;
    end
end
Enlarge_lenaCol = uint8(Enlarge_lenaCol);
figure(2)
imshow(Enlarge_lenaCol)

I want to enlarge the whole image. Not only in one side, I want to make it 512*512.

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Answer 1

Ameer Hamza 2018-5-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/402965-why-i-cant-use-the-same-for-loop-to-interpolate-the-colomn-only-in-row#answer_322342

编辑：Ameer Hamza 2018-5-29

在 MATLAB Online 中打开

You are making a mistake in indexing and length of for loops. Compare it with the following code to see the mistake. Also, there was a typo in two occurrences of Enlarged_le

Lena_half = imread('lena_half.tif');
Row = 512;   % interp1 along row
[m,n,p] = size(Lena_half);
Enlarge_lena = zeros(m, Row, p);
xi = linspace(1, m, Row);
for i = 1:m   % <---- You want to iterate on all rows, not columns
  for j = 1:p
      Enlarged = interp1(1:n,double(Lena_half(i,:,j)),xi);
      Enlarge_lena(i,:,j) = Enlarged;
  end
end
Enlarge_lena = uint8(Enlarge_lena);
figure(1)
imshow(Enlarge_lena)
Col = 512;
[a,b,c] = size(Enlarge_lena);
Enlarge_lenaCol = zeros(Col, b, c);
yi = linspace(1, a, Col);
for d = 1:b  % <--- Iterate on all columns, not rows.
  for o = 1:c
      Enlarged_le = interp1(1:a,double(Enlarge_lena(:,d,o)),yi);  % <-- indexing issue
      Enlarge_lenaCol(:,d,o) = Enlarged_le;  % <-- indexing issue
  end
end
Enlarge_lenaCol = uint8(Enlarge_lenaCol);
figure(2)
imshow(Enlarge_lenaCol)