[argyllcms] Re: How do I force dispcal to always map R0 B0 G0 -> R0 B0 G0 on the calibrated video LUT?

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 22 Dec 2009 00:30:02 +1100

Alexander wrote:

About the -f parameter, what would be usage scenarios to use -f 1.0 or
something like -f 0.5 instead of -f 0. How could I make an educated decision
on the -f value?

It's a bit hard to say. In theory -f 0 should give a more visually uniform
tonal progression, but -f 1 probably matches the natural response of
devices better. All I can suggest is trying these extremes and see
which one gets a better fit, and which one gives a black response
you are looking for.

I believe this may come back to the Eye-One Pro's weakness with
differentiating between very close together dark measurements. Along with
the issue of the Eye-One Pro detecting 0.00cdm2 as 0.05cmd2 randomly on my
CRT. The Eye-One is probably telling Argyll there is a dead zone, even
though I can see with my eyes that there is not. When I am in a dark room
that is obviously inaccurate since the screen is bright grey instead of

I think you are asking a lot of any instrument worth less than $10000,
to expect a good reading below 0.05 cm/d^2. Adaptive mode may improve
things at low levels with the i1pro, although because it then switches
integration time and gain, it may introduce discontinuities.

If would be nice if you could add some sort of override for heuristic, since
it does sounds like it would prove useful for my situation.

dispcal and printcal -V in the next release.

Graeme Gill.

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