[Gimp-developer] unusual (babl/babl/util.h) sRGB tone curve values

[Elle Stone <l elle stone gmail com>]

Working on getting high bit depth color conversion to work (still not
there yet!) has meant peeking into a lot of babl/gegl/gimp code. I
noticed unusual sRGB tone curve values in the functions
"linear_to_gamma_2_2" and "gamma_2_2_to_linear", defined in
/babl/babl/util.h.

The standard values are: 0.04045 and 0.0031308.
The util.h values are:   0.03928 and 0.0030402477.

I was curious as to whether/where/how gimp uses these functions (via
babl, it must be) and why nonstandard values are used.

If anyone is interested, I put together some test code to see what
difference the resulting values might be, given appropriate input
values:
http://ninedegreesbelow.com/temp/gimp-lcms-4.html#srgbtc

Elle
-- 
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