Looping over function string arguments

Asked by Egor on 17 Jun 2014

Latest activity Edited by Egor on 17 Jun 2014

18 views (last 30 days)

The problem is:

%%%%%%%%%%%%%%%%%%%%%%%%%%%This works fine %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%interpolation='bicubic';
interpolation='bilinear';
for scale=1:4
  for image_idx={'01', '02', '03'}
    img_name = strjoin(cellstr(['E:\', image_idx, '.tiff']));
    Iin = imread(img_name);
    ...
    Iout = imresize(Iin, scale, interpolation);
    ...
  end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%This does not %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for interpolation={'bilinear', 'bicubic'}
  for scale=1:4
    for image_idx={'01', '02', '03'}
      ...
      Iout = imresize(Iin, scale, interpolation);
      ...
    end
  end
end

Second case throws an exception:

Index exceeds matrix dimensions.
Error in imresize>parseMethodArg (line 432)
    kernel_width = method{2};
Error in imresize>parseInputs (line 252)
    [params.kernel, params.kernel_width, params.antialiasing] = ...
Error in imresize (line 141)
params = parseInputs(varargin{:});
Error in test_algorithm (line 25)
    Ic = imresize(Ic, scale, interpolation);

0 Comments

1 Answer

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Answer by David Sanchez on 17 Jun 2014

Accepted Answer

In the second method you are passing a cell array as input argument.

Try this:

interpolation={'bilinear', 'bicubic'};
for k=1:numel(interpolation)
  for scale=1:4
    for image_idx={'01', '02', '03'}
      ...
      Iout = imresize(Iin, scale, interpolation{k});
      ...
    end
  end
end

3 Comments

Egor on 17 Jun 2014

No errors so far.

Why does this part work as expected so?

    for image_idx={'01', '02', '03'}
      img_name = strjoin(cellstr(['E:\', image_idx, '.tiff']));

It is iterating over "filelist" without additional indexing, isn't it?

David Sanchez on 17 Jun 2014

They are different command/functions.

strjoin works fine with cell arrays as input arguments.

For any other function, the input arguments has to be a string.

Egor on 17 Jun 2014

Yeah, just 've got it by myself.

Thanks for the help!

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