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

Pierre-Loup A. Griffais pgriffais at
Tue Sep 11 16:04:06 PDT 2012

On 09/11/2012 10:43 AM, Søren Sandmann wrote:
> "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:

One of the items of my (long) list of things to do is to expose anisotropic 
filtering to RENDER, so it'd be cool if that didn't get removed.

  - Pierre-Loup

> that could probably be resurrected.
> Soren

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