[Octave-bug-tracker] [bug #53309] [octave forge] (image) imrotate of +/-90 degrees results in black image when 'crop' and RGB image as input

[Avinoam Kalma]

Update of bug #53309 (project octave):

                  Status:            Works For Me => In Progress            
                 Summary: [octave forge] (image) imrotate of +/-90 degrees
results in black image when 'crop' => [octave forge] (image) imrotate of +/-90
degrees results in black image when 'crop' and RGB image as input

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Follow-up Comment #5:

Thanks for reporting. Checking again, and indeed there is a bug, when the
image is RGB image.

Actually there are few bug in lines 126-131 if imrotate:


      imgPost = zeros(sizePre);
      hw = min(sizePre) / 2 - 0.5;
      imgPost   (round(oPost(2) - hw) : round(oPost(2) + hw),
                 round(oPost(1) - hw) : round(oPost(1) + hw) ) = ...
          imgRot(round(oPost(1) - hw) : round(oPost(1) + hw),
                 round(oPost(2) - hw) : round(oPost(2) + hw) );


1. The class of the output image is not the same as the inputimage
2. The calculation of the parameter hw is not correct for RGB image
3. There is no treatment of RGB image

a fix could be:


      imgPost = zeros(sizePre, class (imgPre));
      hw = min(sizePre(1:2)) / 2 - 0.5;
      if (isgray(imgPre))
        imgPost   (round(oPost(2) - hw) : round(oPost(2) + hw),
                   round(oPost(1) - hw) : round(oPost(1) + hw) ) = ...
            imgRot(round(oPost(1) - hw) : round(oPost(1) + hw),
                   round(oPost(2) - hw) : round(oPost(2) + hw) );
       else
        imgPost   (round(oPost(2) - hw) : round(oPost(2) + hw),
                   round(oPost(1) - hw) : round(oPost(1) + hw), :) = ...
            imgRot(round(oPost(1) - hw) : round(oPost(1) + hw),
                   round(oPost(2) - hw) : round(oPost(2) + hw), :);
       end



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