[Octave-bug-tracker] [bug #61760] [octave forge] (image) imresize - antialiasing is not implemented

[Christof Kaufmann]

Follow-up Comment #9, bug #61760 (project octave):

Thanks for your comments. Anti-aliasing is generally only a thing to prevent
frequency overlap, which can only occur when downscaling. The (new)
documentation says about the property "Antialiasing":
> If this is set to @code{true} and the scale factor in horizontal or vertical
direction is less than 1, anti-aliasing will used for that direction.
And regarding the default value in the same paragraph:
> The default value is @code{true}, except for the method "nearest" / "box".
Maybe we can improve the documentation, if this is not explicit enough. Do you
have any suggestions?

I fixed the typo, that you mentioned. Thanks. (I will provide an updated patch
when our discussion leads to new decisions.)

Regarding Lanczos:
When is version 2.14 due? I would like to know to set the right priorities
regarding the implementations of interp1, interp2, interpn and imresize, and
maybe a simple performance improvement of imremap.
I think I can do better with the textbox Lanczos (by implementing
normalization) and maybe also get closer to the Matlab Lanczos. For that we
could provide:
* lanczos2 (quite matlab compatible, by limiting to "6 taps and 32 phases" and
normalization)
* lanczos2improved (only normalization, more accurate)
* lanczos3 (quite matlab compatible, by limiting to "6 taps and 32 phases" and
normalization)
* lanczos3improved (only normalization, more accurate)
What do you think about that? I have no numbers yet about the differences
though.

I just provided this work-in-progress patch so early to get your opinion on
Lanczos and, maybe, also be able to look at the performance. At least Hartmut
seems very interested in performance according to the discussion in bug
#61845.

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