[Octave-bug-tracker] [bug #51769] [octave forge] (image) imresize bilinear interpolation inaccurate

[Hartmut]

Follow-up Comment #5, bug #51769 (project octave):

Here is the Matlab result on simple sample inputs:


in1 = checkerboard (1,2, 2);

out1 = imresize (in1, 0.5, 'bilinear')   % for Octave (has no antialiasing) 
%out1 = imresize (in1, 0.5, 'bilinear', 'Antialiasing', false) % for Matlab
out1_Matlab = [0.5 0.35; 0.5 0.35]

in2 = checkerboard (1,3, 3);

out2 = imresize (in2, 0.5, 'bilinear')  % for Octave
%out2 = imresize (in, 0.5, 'bilinear', 'Antialiasing', false) % for Matlab
out2_Matlab = [0.5 0.425 0.35; 0.5 0.425 0.35; 0.5 0.425 0.35]


In general I think the approach in comment #1 and comment #4 sounds
reasonable.

I have not understood yet, why you needed to change existing tests in the
code? Where they never Matlab compatible? Did the Matlab result change over
the last years?

Do the results of bicubic interpolation also change with your patch?

To finally review (and hopefully commit in some way) your propsed code change,
we need to wait for Carne, the current image package maintainer.


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