[OctDev] Re: imrotate.m

[Justus P. <Jus...@UL...>]

Great to see that others too are interested in imrotate :-)

Todd, thanks for reporting the half-pixel alignment problem revealed
by the modulo-90 rotations. I think that the cause is incorrect
round-off during computation of the center of rotation and/or the
projection of the corners. I hope to be able to look into this over
the weekend.

In any case, a solution will have to be correct with respect to the
homography (which is sub-pixel accurate when used with
interpolation). In particular, the accelerated versions of the
modulo-90 rotations must produce exactly the same result as the
projection through the homography.

BTW, I submitted a new version of imrotate to octave-dev on February
1st that adds bicubic interpolation and reintegrates Fourier
interpolation.

Cheers,
Justus

--=20
Justus H. Piater, Ph.D.         http://www.montefiore.ulg.ac.be/~piater/
Institut Montefiore, B28        Phone: +32-4-366-2279
Universit=E9 de Li=E8ge, Belgium    Fax:   +32-4-366-2620