[Octave-bug-tracker] [bug #44794] image package: imtransform should use 0 instead of NaN for the default extrapolation value

[H. G.]

URL:
  <http://savannah.gnu.org/bugs/?44794>

                 Summary: image package: imtransform should use 0 instead of
NaN for the default extrapolation value
                 Project: GNU Octave
            Submitted by: hardy
            Submitted on: Do 09 Apr 2015 18:33:09 GMT
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.8.2
        Operating System: Any

    _______________________________________________________

Details:

Here is a little script to show the behavior:


M = [0 1 0; 0 1 0; 0 1 0];
a=45;
t = maketform('affine',[cosd(a) sind(a) 0; -sind(a) cosd(a) 0; 0 1]);
imtrans = imtransform(M,t)


If you run this with the image package (m-files from image-2.4.0 under Octave
3.8.2), then you get this result:


imtrans =

       NaN       NaN       NaN       NaN
       NaN   0.33333   1.00000       NaN
       NaN   1.00000   0.33333       NaN
       NaN       NaN       NaN       NaN


With Matlab you get (slightly different numbers, but that's not the point of
this bug report, and) padded outside with 0 values instead of the NaN values
of Octave.

I think this was fixed for the imrotate, imremap, and imperspectivewarp
functions with the image-2.4.0 release. But it seems to me that it's not fixed
for the imtransform function yet.




    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?44794>

_______________________________________________
  Nachricht gesendet von/durch Savannah
  http://savannah.gnu.org/