[argyllcms] Re: problems hitting white point (color temperature, RGB gain/contrast) while maintaining brightness: dE not stable

  • From: David Heinrich <dh003i@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 16 Dec 2009 14:42:30 -0500

On Tue, Dec 15, 2009 at 5:44 PM, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
>
> If one were to go to a lot of trouble you could measure it
> lots and lots of times and get a more accurate characterization on average,
> but is it worth it ?

With that in mind, I went forward with the device calibration, typing

sudo ./dispcal -v -d1 -yc -t6500 -qh -gs -e5 -P0.5,0.5,3 -o sony-12-15-2009

Here is the summarized result of that; I noticed a bunch of "failed to
meet target maximum error" notes. The full output is on pastebin,
because it is qutie lengthy:

http://pastebin.com/f68cc4978

Doing iteration 2 with 24 sample points and repeat threshold of 0.800000 DE
Failed to meet target 0.800000 delta E, got worst case 0.942560 (avg 0.57)
Doing iteration 3 with 48 sample points and repeat threshold of 0.565685 DE
Failed to meet target 0.565685 delta E, got worst case 1.825335 (avg 0.50)
Doing iteration 4 with 96 sample points and repeat threshold of 0.400000 DE
Failed to meet target 0.400000 delta E, got worst case 1.825335 (avg 0.33)

Doing verify pass with 100 sample points (summary of 5 passes):
patch 100 of 100
Verification results:
Brightness error = -0.662665 to -1.185992 cd/m^2
White point error = 0.464213 to 1.457714 deltaE
Maximum neutral error (@ 0.000000 to 0.987529) = 1.563818 to 2.550708 deltaE
Average neutral error = 0.576811 to 1.090541 deltaE
Number of measurements taken = 100

So is this ok or do the failed to meet target ... delta E's mean the
results I got aren't particularly useful?

PS: Thank you for all of your help, everyone.

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