[Pixman] [PATCH v14 10/22] pixman-filter: Correct integration with impulse filters

Søren Sandmann soren.sandmann at gmail.com
Mon Mar 21 06:36:59 UTC 2016


On Sun, Mar 6, 2016 at 8:06 PM, <spitzak at gmail.com> wrote:

> From: Bill Spitzak <spitzak at gmail.com>
>
> The IMPULSE special-cases did not sample the center of the of the region.
> This
> caused it to sample the filters outside their range, and produce assymetric
> filters and other errors. Fixing this required changing the arguments to
> integral() so the correct point could be determined.
>

I don't understand what is wrong and why this patch fixes it. Which region
precisely did not have its center sampled? When IMPULSE filters are
involved the width of the integral is 0 so there isn't really any "region"
to sample.

Can you give a concrete example where the previous code produced asymmetric
filters? Also, what "other errors" was produced? I think these examples
should be added to the commit log.


Søren
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