Re: Color Calibration

[Ken Harris <ken bitpoetry com>]

Hi Manuel,

> It seems not to work at all on dumb terminals.  I've just compiled and
> tried to use it, and sliding the three sliders below the feet did
> nothing.

I obviously can't tell for sure based on this, but this is probably your
video system's fault.  I tell XFree86 to set the gamma, and XFree86
tells your card, but if your card doesn't do anything with this value,
there's (a) no way to know, and (b) nothing I can really do about it.

A quick way to test is to try 'xgamma' with a few values.  ("xgamma
-gamma 1.0" and 1.5 and 2.0.)  If xgamma doesn't do anything, it's your
video card's fault (or possibly the driver, but that seems unlikely). 
(I should add this to the README, or maybe a TROUBLESHOOTING file.)

For the next version, I'm including a note (about video cards ignoring
gamma) if you have multiple displays.  Many (most? all?) graphics cards
supported by XFree86 simply ignore the gamma for all but the first
display.  (Perhaps I'll show the note even if you have only one
display.)

> I also cannot understand what the "target gamma" means =(

I'm not sure there's an easy way to describe it.  That's why I listed
the Mac and PC standard values, and made the default a reasonable
value.  Do you want your display to display graphics like a Mac or a PC?

I've received the message loud and clear, though: people get confused on
the target gamma step.


- Ken