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

Daniel Stone daniel at
Tue Sep 11 04:08:10 PDT 2012


On 11 September 2012 03:17, Pierre-Loup A. Griffais
<pgriffais at> wrote:
> On 09/10/2012 06:08 PM, Daniel Stone wrote:
>> 'Best' might be bicubic.  It might be nearest.  It might be anything,
>> it's just whatever the driver thinks will offer the best quality.
>> Bicubic is not required to be offered, but it may be.
> 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.

None of Intel UXA, Radeon EXA or Nouveau EXA accelerate convolutions.
They're not particularly widely used anyway (at least by Cairo et al),
probably because no-one accelerates them.


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