gamma correction

[Martijn Sipkema]

I've been thinking some more about gamma correction...

- (almost) no hardware can do per window gamma correction, i.e.
gamma corrected and uncorrected visuals.
- most systems don't do full gamma correction in the framebuffer
LUT. SGI has a default system gamma of 1.5, Mac uses 1.8. I
suppose Windows uses 2.2.
- With 8 bits per RGB channel on a fully gamma corrected display
the resolution is somewhat low for dark colors (though I don't think
unusable).

A reasonable solution might be to use the SGI system gamma of
1.5 (gamma correction between 1.3 and 1.7 depending on the
monitor). This seems like a reasonable compromise between speed
and quality.

An application shouldn't assume a certain system gamma IMHO. On
graphics hardware with more than 8 bits per RGB channel one might
want to run with a system gamma of 1 and one might want to run
at 2.2 for backwards compatibility. Is there a standard way to get
the system gamma under X11?

PS.

I noted while testing that once enabled I can't disable polygon
stippling on my matrox G400 (DRI/XFree86).

--ms