[argyllcms] Re: Pioneer Kuro Plasma calibration with dispcal
- From: Fatcat <molotok@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 14 Jan 2014 19:07:11 +0400
> Hmm. That doesn't really explain the inconsistent black measurement values -
> they were going up and down together.
Yes indeed. I was being dumb again. Between different colors there had to be a
huge delta, more than "1". It turned out I didn't put the tool into emissive
mode with spotread -V -e and it was shining its light onto the display every
time. I didn't see it as it was on a plate but you get the idea.
Anyhow, now that it's been sorted out, I repeated the measurements and still
got weird results. Lighter patches behaved well. Problems started when I got to
12.5% gray. First few measurements if taken right one after another fall into
dE<1, however each 7 seconds passed bump up the delta by about 0.15. So in
about a minute the error is 1 and growing.
Take a look at this log. Most of the measurements were done in approx 7 second
intervals, for a couple others I waited 30 seconds or more.
Result is XYZ: 3.433451 3.111993 2.344613, D50 Lab: 20.486948 7.225649 1.872451
XYZ stats 2: Avg 1.716726 1.555997 1.172307, S.Dev 1.716726 1.555997 1.172307
Lab stats 2: Avg 20.440763 7.155485 1.849416, S.Dev 0.046185 0.070164 0.023034
Delta E to reference is 0.092369 0.140328 0.046068 (0.174202, CIE94 0.144358)
Result is XYZ: 3.464347 3.136593 2.354093, D50 Lab: 20.582838 7.304263 1.955632
XYZ stats 3: Avg 2.299266 2.082862 1.566235, S.Dev 1.625875 1.472840 1.107502
Lab stats 3: Avg 20.488121 7.205077 1.884822, S.Dev 0.076861 0.090559 0.053486
Delta E to reference is 0.188259 0.218943 0.129250 (0.316359, CIE94 0.270037)
Result is XYZ: 3.488935 3.157684 2.373800, D50 Lab: 20.664651 7.341036 1.926614
XYZ stats 4: Avg 2.596683 2.351568 1.768126, S.Dev 1.499325 1.357775 1.020883
Lab stats 4: Avg 20.532254 7.239067 1.895270, S.Dev 0.101359 0.098064 0.049730
Delta E to reference is 0.270072 0.255715 0.100232 (0.385196, CIE94 0.339866)
Result is XYZ: 3.508866 3.184143 2.380671, D50 Lab: 20.766773 7.215173 2.043605
XYZ stats 5: Avg 2.779120 2.518083 1.890635, S.Dev 1.389788 1.259266 0.945407
Lab stats 5: Avg 20.579158 7.234288 1.924937, S.Dev 0.130456 0.088230 0.074155
Delta E to reference is 0.372194 0.129853 0.217223 (0.450085, CIE94 0.426851)
Result is XYZ: 3.532099 3.199592 2.403693, D50 Lab: 20.826140 7.324170 1.948846
XYZ stats 6: Avg 2.904616 2.631668 1.976145, S.Dev 1.299361 1.177271 0.883962
Lab stats 6: Avg 20.620321 7.249269 1.928922, S.Dev 0.150515 0.087231 0.068278
Delta E to reference is 0.431561 0.238850 0.122464 (0.508224, CIE94 0.476966)
Result is XYZ: 3.560888 3.220095 2.420917, D50 Lab: 20.904632 7.435783 1.937529
XYZ stats 7: Avg 2.998369 2.715729 2.039684, S.Dev 1.224699 1.109220 0.833057
Lab stats 7: Avg 20.660937 7.275913 1.930151, S.Dev 0.171219 0.103836 0.063285
Delta E to reference is 0.510053 0.350462 0.111147 (0.628754, CIE94 0.579503)
Result is XYZ: 3.596509 3.250594 2.431842, D50 Lab: 21.020782 7.488515 2.045121
XYZ stats 8: Avg 3.073137 2.782587 2.088704, S.Dev 1.162554 1.052551 0.789973
Lab stats 8: Avg 20.705918 7.302489 1.944523, S.Dev 0.199535 0.119908 0.070357
Delta E to reference is 0.626203 0.403194 0.218739 (0.776236, CIE94 0.715800)
Result is XYZ: 3.619652 3.271293 2.440567, D50 Lab: 21.099193 7.508098 2.106518
XYZ stats 9: Avg 3.133861 2.836888 2.127800, S.Dev 1.109442 1.004169 0.752958
Lab stats 9: Avg 20.749615 7.325334 1.962522, S.Dev 0.225091 0.130214 0.083618
Delta E to reference is 0.704614 0.422777 0.280136 (0.868158, CIE94 0.803858)
Result is XYZ: 3.648941 3.296127 2.468061, D50 Lab: 21.192836 7.554822 2.036550
XYZ stats 10: Avg 3.185369 2.882811 2.161826, S.Dev 1.063792 0.962549 0.721575
Lab stats 10: Avg 20.793937 7.348283 1.969925, S.Dev 0.251554 0.141421 0.082377
Delta E to reference is 0.798258 0.469501 0.210168 (0.949640, CIE94 0.886685)
Result is XYZ: 3.663369 3.312242 2.472111, D50 Lab: 21.253351 7.514939 2.106942
XYZ stats 11: Avg 3.228823 2.921851 2.190033, S.Dev 1.023552 0.926021 0.693753
Lab stats 11: Avg 20.835702 7.363433 1.982381, S.Dev 0.273806 0.143098 0.087867
Delta E to reference is 0.858773 0.429618 0.280560 (1.000388, CIE94 0.943632)
Result is XYZ: 3.707172 3.351061 2.491290, D50 Lab: 21.398322 7.557369 2.196651
XYZ stats 12: Avg 3.268686 2.957618 2.215138, S.Dev 0.988854 0.894498 0.669417
Lab stats 12: Avg 20.882587 7.379595 2.000237, S.Dev 0.304799 0.147118 0.102880
Delta E to reference is 1.003743 0.472048 0.370269 (1.169371, CIE94 1.104988)
Result is XYZ: 3.793729 3.421588 2.540008, D50 Lab: 21.658864 7.737666 2.242491
XYZ stats 13: Avg 3.309074 2.993308 2.240128, S.Dev 0.960307 0.868253 0.648955
Lab stats 13: Avg 20.942301 7.407139 2.018872, S.Dev 0.358532 0.170537 0.118056
Delta E to reference is 1.264285 0.652346 0.416109 (1.482268, CIE94 1.393668)
Result is XYZ: 3.870434 3.487317 2.584398, D50 Lab: 21.898479 7.843338 2.292556
XYZ stats 14: Avg 3.349171 3.028594 2.264719, S.Dev 0.936600 0.846288 0.631602
Lab stats 14: Avg 21.010599 7.438296 2.038421, S.Dev 0.424269 0.199061 0.133828
Delta E to reference is 1.503901 0.758018 0.466174 (1.747463, CIE94 1.647151)
Result is XYZ: 3.915744 3.523240 2.604879, D50 Lab: 22.028169 7.949798 2.350045
XYZ stats 15: Avg 3.386942 3.061571 2.287396, S.Dev 0.915812 0.826850 0.616057
Lab stats 15: Avg 21.078437 7.472396 2.059196, S.Dev 0.482112 0.230788 0.150858
Delta E to reference is 1.633590 0.864478 0.523663 (1.920979, CIE94 1.802147)
Result is XYZ: 3.995982 3.594777 2.631200, D50 Lab: 22.283822 8.013811 2.578611
XYZ stats 16: Avg 3.425007 3.094896 2.308884, S.Dev 0.898903 0.810931 0.602272
Lab stats 16: Avg 21.153774 7.506234 2.091659, S.Dev 0.550489 0.259056 0.192728
Delta E to reference is 1.889243 0.928491 0.752229 (2.235438, CIE94 2.098486)
Result is XYZ: 4.795754 4.280721 3.061744, D50 Lab: 24.578590 8.971767 3.248750
XYZ stats 18: Avg 3.577216 3.226345 2.392413, S.Dev 0.950572 0.850160 0.615017
Lab stats 18: Avg 21.533330 7.672059 2.219422, S.Dev 1.192427 0.528881 0.404487
Delta E to reference is 4.184011 1.886447 1.422368 (4.804972, CIE94 4.540831)
The value is constantly drifting. More so in the luminance channel it seems.
Several hours later I repeated the measurements and got the same pattern, the
values were constantly drifting albeit slower. On the same 12.5% patch it took
me about 4 minutes to get to dE 1. What's interesting is that between
subsequent measurements the difference usually doesn't exceed dE 0.3.
The drift is faster on dark patches while on lighter ones it's much slower
although still present. On some patches it takes about half a minute for the
plasma to stabilize, i.e. you change the color, immediately take a measurement,
set it as a reference point and the value starts immediately drifting, after 30
seconds the error is about 0.3 and from then on increases slowly. On a cyan
patch this initial drift was only present in L and b channels, but absent in a.
I can't interpret these results at all. What I understand is that given the
small error between measurements for me it probably would be better to use a
mode with very few crosschecks but instead pausing after changing color and
before taking the actual measurement. It's interesting to know your thoughts on
the matter.
Zakhar
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