[argyllcms] Re: Calibration speed issue.

  • From: James Freeman <jamesilyafreeman@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 21 Apr 2014 11:15:30 +0300

I already use madTPG.
I think the problem is in the very low expected dE in the lower black shades. If you remember I contacted you about lower than native contrast ratio after calibration, and you fixed this by lowering the expected calibration dE in the darker shades.
This fixed the Contrast Ratio but made the calibration time twice as long.
Some times it takes 10 attempts for a single shade of black, other times it just fails to reach the extremely low expected dE and gives up (in the log).

If you can, please change the calibration dE behavior to what it was in version 1.6.0/1 so that calibration will be faster (like it was). I will just change the 0.000 step to 0.00, 0.00, 0.00 in the .CAL file to preserve the Contrasts Ratio.

Thanks


On Mon 21.Apr.2014 10:56, Graeme Gill wrote:
James Ilya Freeman wrote:

Are you planing to fix this issue or leave it as is?
Hi,
        well it would be good to fix it, but I'm not really sure how to. I
don't have any examples of this behavior to investigate, since it depends
on the interaction of the calibration algorithm and the particular display.

A possible direction to investigate would be to see if using dithering
in the test patches may speed the iterations up.

You could provide some feedback on this idea if you could try using the
MadTPG as the patch color source, and see if that helps your situation.

See <http://forum.doom9.org/showthread.php?t=146228>

Graeme Gill.




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