On Tue, Feb 2, 2016 at 8:28 AM, <spit...@gmail.com> wrote: > From: Bill Spitzak <spit...@gmail.com> > > The SIGMA term drops out on simplification. > > Expanded the size slightly (from ~4.25 to 5) to make the cutoff less > noticable. > The filter is truncated at a value of .001 instead of .006, this new > value is less than 1/2 of 1/255, rather than greater than it.
I'm just wondering how did you get to this result ? Oded > > Signed-off-by: Bill Spitzak <spit...@gmail.com> > > Acked-by: Oded Gabbay <oded.gab...@gmail.com> > --- > pixman/pixman-filter.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c > index b6f8eb4..10fa398 100644 > --- a/pixman/pixman-filter.c > +++ b/pixman/pixman-filter.c > @@ -63,10 +63,7 @@ linear_kernel (double x) > static double > gaussian_kernel (double x) > { > -#define SQRT2 (1.4142135623730950488016887242096980785696718753769480) > -#define SIGMA (SQRT2 / 2.0) > - > - return exp (- x * x / (2 * SIGMA * SIGMA)) / (SIGMA * sqrt (2.0 * M_PI)); > + return exp (- x * x) / sqrt (M_PI); > } > > static double > @@ -139,7 +136,7 @@ static const filter_info_t filters[] = > { PIXMAN_KERNEL_BOX, box_kernel, 1.0 }, > { PIXMAN_KERNEL_LINEAR, linear_kernel, 2.0 }, > { PIXMAN_KERNEL_CUBIC, cubic_kernel, 4.0 }, > - { PIXMAN_KERNEL_GAUSSIAN, gaussian_kernel, 6 * SIGMA }, > + { PIXMAN_KERNEL_GAUSSIAN, gaussian_kernel, 5.0 }, > { PIXMAN_KERNEL_LANCZOS2, lanczos2_kernel, 4.0 }, > { PIXMAN_KERNEL_LANCZOS3, lanczos3_kernel, 6.0 }, > { PIXMAN_KERNEL_LANCZOS3_STRETCHED, nice_kernel, 8.0 }, > -- > 1.9.1 > > _______________________________________________ > Pixman mailing list > Pixman@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/pixman _______________________________________________ Pixman mailing list Pixman@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/pixman