[cairo] Concerns about using filters for downscaling

[Søren Sandmann]

Owen Taylor <otaylor at redhat.com> writes:

> (Søren pointed out on IRC that the pixman implemention of convolution
> is not SIMD optimized, so their would be future opportunity to improve
> what we can do within the constraints of 5-10x slower.)

Also, the pixman convolution filter is designed to be implemented in a
separable way, but the current code doesn't do that. This optimization
should be another major speedup for filters with wide support such as as
Lanczos.


Søren