[Mesa-dev] [PATCH] nir/lower_tex: Fix minor error in YUV color conversion matrix

[Jason Ekstrand]

On Wed, May 3, 2017 at 11:53 PM, Kenneth Graunke <kenneth at whitecape.org>
wrote:

> On Wednesday, May 3, 2017 11:37:52 PM PDT Johnson Lin wrote:
> > The matrix used for YCbCr to RGB is listed in:
> >
> > https://en.wikipedia.org/wiki/YCbCr
> >
> > There was an error in converting the offsets from integers to unorm
> > values: 0.0625=16/256 should be 16.0/255,and 0.5=128.0/256 should be
> > 128.0/255.  With this fix, the CSC result is bit aligned with wikipedia's
> > conversion result and FFMPeg's result.
> > ---
> >  src/compiler/nir/nir_lower_tex.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/compiler/nir/nir_lower_tex.c
> b/src/compiler/nir/nir_lower_tex.c
> > index 352d1499bc8d..4ef81955513e 100644
> > --- a/src/compiler/nir/nir_lower_tex.c
> > +++ b/src/compiler/nir/nir_lower_tex.c
> > @@ -244,9 +244,9 @@ convert_yuv_to_rgb(nir_builder *b, nir_tex_instr
> *tex,
> >     nir_ssa_def *yuv =
> >        nir_vec4(b,
> >                 nir_fmul(b, nir_imm_float(b, 1.16438356f),
> > -                        nir_fadd(b, y, nir_imm_float(b, -0.0625f))),
> > -               nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -0.5f)),
> 0),
> > -               nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -0.5f)),
> 0),
> > +                        nir_fadd(b, y, nir_imm_float(b, -16.0f /
> 255.0f))),
> > +               nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -128.0f /
> 255.0f)), 0),
> > +               nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -128.0f /
> 255.0f)), 0),
> >                 nir_imm_float(b, 0.0));
> >
> >     nir_ssa_def *red = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[0]));
> > --
> > 1.9.1
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >
>
> I scooped up the various tags:
>
>     Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100854
>     Reviewed-by: Eric Anholt <eric at anholt.net>
>     Reviewed-by: Kristian H. Kristensen <hoegsberg at google.com>
>

Did you also scoop up a stable CC?
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