https://bugs.freedesktop.org/show_bug.cgi?id=46631
Kurt Roeckx <k...@roeckx.be> changed:
What |Removed |Added
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CC| |k...@roeckx.be
--- Comment #7 from Kurt Roeckx <k...@roeckx.be> 2012-02-26 11:52:37 PST ---
(In reply to comment #6)
>
> This seems wrong. If you specify luminance as 1 and read back luminance, you
> should receive 1.
That makes sense to me too.
> If you're reading GL_LUMINANCE from an RGB texture, adding the values L = R +
> G
> + B is certainly conformant
I understand things it should do:
Y = (R*RedScale+RedBias)+(G*GreenScale+GreenBias)+(B*BlueScale+BlueBias)
Where you would normally want to set the scales to something sane, like 0.299,
0.587, 0.114.
Settings like 1/3 for the scales don't make sense to me if you really want
luminance, but would clearly be better than the default of 1. With a scale
of 1 you would have a problem with the clamping to [0,1].
> If you supply RGB values to TexImage, you would have to supply (for instance)
> R
> = G = B = 1/3 to achieve luminance 1, and adding those 3 * 1/3 back together
> ... it's a bug in mesa.
No, you set R, G and B to 1, and set the scales with glPixelTransferf() to get
the desired effect.
Kurt
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