[Gegl-developer] Passing parameter to sampler from XML file

[Nicolas Robidoux]

Øyvind Kolås writes:
 > 
 > I would feel more comfortable if this parameter was not exposed, but
 > rather that sane presets were added and given names. In most cases the
 > additional properties of for instance a displacement map operation
 > might be visual and conceptual clutter getting in the users way. When
 > it comes to naming it; I think perhaps smoothing is a good candidate.
 > 

You mean, like the "type" for gegl-sampler-cubic, which sets the B and
C values based on named bicubic variants?

For example, nohalo1 (same result as snohalo1 with smoothing = 0, but
runs faster) would be "sharper", snohalo1 with smoothing = 1 would be
"smoother", and snohalo1 with smoothing = .5 would be "halfandhalf,"
or something kind of like that?

Likewise with nohalobox (the scheme tuned for downsampling)?

You can see samples of what "sharper" and "smoother" would be at
http://gsoc.rivetsforbreakfast.com/enlargements.html

Note that because s/nohalo is nonlinear, smoothing = .5 does not give
the average of the sharper and smoother results.

(Note that levels more or less correspond to quality level. Higher
levels are not yet implemented.)

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This was my vision (hubris?) or where this would all eventually go
(keeping the smoothing parameter visible):

There would be a slider corresponding to the amount of custom
smoothing being applied (of course, this would do nothing to nearest
neighbour and bilinear) for s/nohalo and nohalobox.

The user would look at the results (depends on noisiness of resampled
image, whether there is much warping going on or only up/downsampling,
whether there are a lot of text/perfectly horizontal/vertical lines,
amount of visibly annoying aliasing, whether it's for print or the
web, etc) and adjust the slider until, hopefully, she are happy.

Comments?

Nicolas Robidoux
University Laurentienne