Re: [Gimp-developer] Cubic Interpolation vs No Halo

[Øyvind Kolås <pippin gimp org>]

On Mon, May 9, 2016 at 12:11 PM, Karl Günter Wünsch
<kgw mineralien-verkauf de> wrote:
> On 07/05/16 15:38, Øyvind Kolås wrote:
> > I've pushed code to GEGL master that makes the resamplers called
> > "linear" and "cubic" do a tiny bit more than just interpolation.
>
> The more you change the default behavior of existing filters the more it
> makes the use of GIMP impossible in a setup where you build up a
> workflow... It's bad enough to outright drop the previously available
> scaling algorithm but to tinker and thus in some cases invalidate
> existing workflows without the user being made aware of it is ridiculous
> for a tool like the GIMP...

This was a fix for the 2.9 series - any releases of 2.9 thus far have
been development snapshots and you shouldn't be establishing
unchangable workflows based on the behavior of development snapshots.
The new behavior you will get from cubic and linear *resamplers* in
GIMP master + GEGL master resembles what the stable releases of GIMP
have been doing for at least the last half decade, whereas GIMP 2.9
for a while has produced the equivalent of slightly randomized nearest
neighbor when scaling down with cubic and linear. Other things that
might happen for 2.10 is lanczos being reinstated if *you (or someone
you convince)* implement lanczos as a GeglSampler, and the nohalo
sampler being dropped unless it starts having performance of similar
magnitude to nearest/linear/cubic/lohalo.

> I would ask you to reinstate the old code and have the new selectable
> under a new name - then at least an existing workflow could remain
> intact and the user would be made aware (a little bit at least) that
> there may be something better available...

Nope - won't happen. Linear and cubic resamplers should provide
reasonable results - instead of a random broken thing, which is why I
also implemented similar fixes to GIMP itself early in the 2.x series.
If you've been blurring your photos before scaling them down with
cubic to compensate for cubic being broken in 2.9, you should no
longer be doing so.

/pippin