Question about future direction for resamplers:

Would it be better if there was only one sampler tuned for upsampling,
and one tuned for downsampling?

My previous vision for GEGL was that my research group would
contribute TWO resamplers tuned for upsampling and TWO resamplers
tuned for downsampling. The four new samplers would (eventually)
integrate the best of the 16 resamplers programmed by Eric and Adam
for GSoC 2009.  Within each of the two pairs of resamplers, one was to
be "interpolatory" (and more aliased) and the other would minimally
blur (and be less aliased).

Now: I just figured out how to use the Jacobian matrix information so
that the sampler only add noticeable antialiasing blur when the
operation is performing significant upsampling or downsampling. What
this means for the resamplers tuned for upsampling, for example, is
that we could seamlessly integrate Nohalo and Snohalo in such a way
that the sampler behaves like Nohalo when translating and rotating
(hence is "blur free") but behaves increasingly like Snohalo as the
transformation (locally) deviates from being distance preserving
(hence is more anti-aliased), resulting in one single sampler which
would please everyone and their father.

I imagine that a few people would want the added control over the
aliasing vs blur trade-off which having pairs of methods would provide
(also, methods can be faster if they are not jack of all trades).

But I am wondering if for GEGL's target user base an "always pretty
good" default is preferable to "choose your poison."


Nicolas Robidoux
Universite Laurentienne
Gegl-developer mailing list

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