[Image-SIG] downscaling by area averaging
Fredrik Lundh
fredrik at pythonware.com
Fri May 6 12:26:34 CEST 2005
Douglas Bagnall wrote:
> I've made a patch to resize by averaging pixels.
>
> http://halo.gen.nz/pil/pil_area_average.patch
>
> If people want it, I'll fix up the GCCisms, and make it work on other
> than RGB images.
looks interesting, but in theory (and without analyzing your
code), shouldn't this be the same as running ImagingStretch
with the nearest filter? (=an adaptive box filter)
(guess I'll have to do some experiments... I've been meaning to
switch to ImagingStretch for all downsampling uses, but haven't
had time to tune the filters yet (=make them behave the same
as the upsampling filters). this might be the prodding I needed)
> Interestingly, the area averaged image is generally pixel perfect with
> the Gimp's best resizing ("Cubic").
that's odd. what kind of source images are you processing?
</F>
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