Re: [Gimp-developer] Tuning and choosing resampling methods in GEGL/GIMP

[Elle Stone <ellestone ninedegreesbelow com>]

On 10/23/2017 09:13 AM, Øyvind Kolås wrote:
> The actual reason for this email is that I think it might be overkill
> to have both lohalo and nohalo available as choices, they are related
> and powerful transformation ellipsis aware methods, maybe it is
> sufficient to have one go-to high quality resampler instead of
> expecting the user to make a choice between lohalo and nohalo on a
> case by case or built up as general preference, and in which case I
> believe of these two related methods, from Nicolas Robidoux &
> collaborators, we'd be best off keeping the nohalo method - possibly
> with an adaptive _OFFSET0 to speed resampling that is primarily
> interpolatory.

Hi Pippin,

Agreeing with what you say, I've tried lohalo and never saw any reason 
to use it instead of nohalo. For several years now nohalo is the only 
downsizing method that I use.

I see in the git log that some changes have been made recently to 
nohalo. I haven't used the new version of nohalo, and also haven't added 
these changes to my "CCE" version of GIMP. The reason I mention this is 
because even though nohalo (the older version of nohalo) is slow, it 
produces results that are exceptionally good.

The recent GEGL commit 0b0ecbb67198d6318ed163522e5233ecbc18ff25 mentions 
slightly sharper results for nohalo: "for sigificant downsampling this 
might result in sharper/aliased results".

This "sharper/aliased results" doesn't sound like a good thing, at least 
not for my particular workflow. I don't use a lot of sharpening in my 
workflow, and I prefer to do any required post-downsizing sharpening by 
hand, using masks and layers, and using either unsharp mask or high pass 
sharpening, on an image by image basis.

Would there be the possibility of parameters with the revised nohalo 
that would allow to replicate the old results?

Best,
Elle