[argyllcms] Re: Gamma wrong for calibration curves?

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 01 Dec 2006 13:55:33 +1100

William Wood wrote:

dispcal switched the color patch.  (It would be nice if there was a dispcal
flag to measure the display as calibrated!)

OK, I'll see about adding that as an option to "-r".

Aprox. gamma = 2.01

Ah, well, I think what you've noticed is that between the
first release of dispcal and the current one, I changed how
the black point was being dealt with. I was originally
subtracting it from all the measurements, but in the current
version the curves are computed in relation to absolute zero.
The "Approximate Gamma" calculation is still subtracting black,
and this may explain the discrepancy between the aim point,
and the value you measured. I'll fix the code to be
consistent for the next release.

Graeme Gill.

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