[Octave-bug-tracker] [bug #55780] [octave forge] (image) imresize with 'cubic' option is very wrong

[Avinoam Kalma]

Update of bug #55780 (project octave):

                  Status:                    None => Confirmed              
                 Release:                   4.4.1 => dev                    
        Operating System:               GNU/Linux => Any                    

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Follow-up Comment #1:

The problem seems to be from graybicubic call in grayinterp (imremap.m)


function [warped, valid] = grayinterp(im, XI, YI, interp, extrapval)
  if (strcmp(interp, "cubic"))
    warped = graybicubic(double(im), XI, YI, 0);
  else
    warped = interp2(double(im), XI, YI, interp, 0);
  endif
  valid = !isna(warped);
  warped(!valid) = extrapval;
endfunction


If we use interp2 in the case of cubic interpolation:

function [warped, valid] = grayinterp(im, XI, YI, interp, extrapval)
%  if (strcmp(interp, "cubic"))
%    warped = graybicubic(double(im), XI, YI, 0);
%  else
    warped = interp2(double(im), XI, YI, interp, 0);
%  endif
  valid = !isna(warped);
  warped(!valid) = extrapval;
endfunction

The result looks better.



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