Does Xorg'x XRender implementation support "better-than-bilinear" interpolation?

Søren Sandmann sandmann at
Tue Sep 11 10:43:40 PDT 2012

"Pierre-Loup A. Griffais" <pgriffais at> writes:

> I'm not very familiar with bicubic interpolation, but couldn't it be
> achieved using the 'convolution' filter with the adequate kernel?
> (possibly in several passes at different scales). AFAIK 'convolution'
> is always provided and often accelerated.

The convolution filter in Render only allows one phase of the filter to
be used, so the quality of bicubic interpolation implemented that way
would be terrible.

As an aside, a bunch of code could be deleted if we removed the ability
for drivers to provide their own filters. As far as I know, no driver
has ever done this. I have an old branch here:

that could probably be resurrected.


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