Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: Dinarius on February 20, 2017, 05:00:37 am
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I can't find the answer to this anywhere.
Which patch do I use to create a white balance with this (http://xritephoto.com/colorchecker-digital-sg) chart?
Many thanks.
D.
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I can't find the answer to this anywhere.
Which patch do I use to create a white balance with this (http://xritephoto.com/colorchecker-digital-sg) chart?
Many thanks.
D.
It depends on how you expose and what camera you use. If you ETTR to the clipping and your camera is not linear in the top range then any mid-grey patch will go since spectrally all neutral patches of SG must be flat -the white, grey and black. Note however that the illuminantion across the target must be very even both spectrally and luminancewise.
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I can't find the answer to this anywhere.
Which patch do I use to create a white balance with this (http://xritephoto.com/colorchecker-digital-sg) chart?
F5 should work, but there are relatively neutral patches all along the edge of the grid as well.
Cheers,
Bart.
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I can't find the answer to this anywhere.
Which patch do I use to create a white balance with this (http://xritephoto.com/colorchecker-digital-sg) chart?
Many thanks.
D.
http://xritephoto.com/ph_product_overview.aspx?ID=938&Action=Support&SupportID=5884
patch L* a* b* for new (>= 11/2014) SG
H6 60.04 0.09 0.05
K6 70.6 -0.24 0.07
G5 65.22 -0.27 0.16
I6 75.36 0.35 0.26
F5 79.65 -0.08 0.62
if you believe X-Rite data of course (nobody knows how exactly they measured and then it was, I bet, just one specimen)
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I can't find the answer to this anywhere.
Which patch do I use to create a white balance with this (http://xritephoto.com/colorchecker-digital-sg) chart?
RawDigger authors (https://www.rawdigger.com/howtouse/prepare-data-for-profiling) recommend G5 patch for white balancing
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RawDigger authors (https://www.rawdigger.com/howtouse/prepare-data-for-profiling) recommend G5 patch for white balancing
G5 was probably for pre Nov 2014 target (with all the fine print about the measurements), based on its brightness (reflectance) vs deviation from neutrality.
E10 49.7 -0.19 0.01
A3 49.7 -0.18 0.03
B1 49.72 -0.19 0.02
K10 49.72 -0.19 0.02
N2 49.69 -0.18 0.03
A6 49.66 -0.2 0.01
B10 49.69 -0.2 0.01
E1 49.74 -0.19 0.03
H1 49.75 -0.21 0.01
H10 49.7 -0.2 0.02
N5 49.72 -0.18 0.05
H5 49.71 -0.2 0.03
K1 49.79 -0.2 0.03
M1 49.77 -0.19 0.04
M10 49.68 -0.19 0.05
A9 49.72 -0.2 0.04
N8 49.7 -0.19 0.07
K7 45.59 -0.05 0.23
E6 6.66 0 -0.3
A8 6.49 -0.02 -0.28
G5 65.05 0 -0.32
I5 35.26 -0.09 -0.24
N3 6.39 -0.04 -0.33
N9 6.47 0 -0.38
K8 20.3 0.07 -0.32
K6 70.76 0.07 -0.35
N6 6.49 -0.03 -0.41
I6 75.16 0.25 -0.2
PS: counting angels on the proverbial pinhead
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G5 was probably for pre Nov 2014 target (with all the fine print about the measurements), based on its brightness (reflectance) vs deviation from neutrality.
And there is the issue of brightness as well. White balancing is preferably done with a relatively bright patch, which also automatically improves the Signal to Noise Ratio of the measurement.
Cheers,
Bart
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And there is the issue of brightness as well. White balancing is preferably done with a relatively bright patch, which also automatically improves the Signal to Noise Ratio of the measurement.
White balancing has less to do with brightness and more with neutrality. Perhaps if the raw converter use one click correction (you click the patch, it adjusts WB and exposure) then the brightness matter
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And there is the issue of brightness as well. White balancing is preferably done with a relatively bright patch, which also automatically improves the Signal to Noise Ratio of the measurement.
Cheers,
Bart
one might also add the line about "WB tool" used - how many pixels it is averaging which depends on the software used (1x1, 3x3, 5x5, etc)
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G5 was probably for pre Nov 2014 target (with all the fine print about the measurements), based on its brightness (reflectance) vs deviation from neutrality.
In those numbers yes H6 looks better but I prefer to measure my targets with Spectrolino or i1 Pro
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with Spectrolino
and how do you keep reheating the lamp there (in the said spectrolino) to deal with tungsten deposits while measuring the target like SG ?
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And there is the issue of brightness as well. White balancing is preferably done with a relatively bright patch, which also automatically improves the Signal to Noise Ratio of the measurement.
Cheers,
Bart
Yes, that's why I use the brightest gray patch. Another issue with the SG is specular reflection of a tinted illuminant that can be from a colored, bright surface in the environment that happens to line up with reflective SG surface. That effect is particularly important to avoid when using the SG to create a camera profile as it can desaturate and shift colors on the darker patches a large amount.
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and how do you keep reheating the lamp there (in the said spectrolino) to deal with tungsten deposits while measuring the target like SG ?
I don't (I average several target measurements) - does it have the same problem like i1 Pro v2? Any measurements/data to support that?
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I don't (I average several target measurements) - does it have the same problem like i1 Pro v2? Any measurements/data to support that?
yes, it has a noticeable drift, you saw that topic = http://forum.luminous-landscape.com/index.php?topic=108238
for i1Pro* there are API calls (or workarounds) to instruct the spectrometer to heat its lamp from software on demand
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yes, it has a noticeable drift, you saw that topic = http://forum.luminous-landscape.com/index.php?topic=108238
What I saw there was this statement from Graeme
I've seen similar effects on all my i1Pro's, and also Spectrolino's,
although none as dramatic as the Rev E was.
And my experiments do not show a large discrepancies benween the measurements on my Spectrolino and i1 Pro rev D that I have.
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What I saw there was this statement from Graeme
And my experiments do not show a large discrepancies benween the measurements on my Spectrolino and i1 Pro rev D that I have.
that topic has Spectrolino test with graph... and iPro2 test with graph... " b* " drift for Spectrolio is big.
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that topic has Spectrolino test with graph... and iPro2 test with graph... " b* " drift for Spectrolio is big.
Have you read the post with follow up Spectrolino diagrams after that one? Where calibrations were performed?
With Spectrolino automated measurements it does force recalibrations fairly frequently - possibly to account for the drift.
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Have you read the post with follow up Spectrolino diagrams after that one? Where calibrations were performed?
which post ? I am referring to the graphs in the following post http://forum.luminous-landscape.com/index.php?topic=108238.msg892565#msg892565
With Spectrolino automated measurements it does force recalibrations fairly frequently - possibly to account for the drift.
with spectroscan table you most probably keep the lamp heated good enough by measuring printed target patch by patch in a quick succession - you can't do the same manually with SG...
whether standard calibration helps or not like the heating request - I think we can do the test... say execute calibration every 10th (or may be even every other) measurement... I need to dig out my Spectrolino... what is clear though that you can't calibrate once before measuring the whole big target
PS: what is also interesting to test is to see how different is drift say between repeated measurements of dark patch (allegedly the lamp is on for a longer duration) and bright patch (allegedly the lamp is on for a shorter duration)
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which post ? I am referring to the graphs in the following post http://forum.luminous-landscape.com/index.php?topic=108238.msg892565#msg892565
That one - and it shows b* drift of 0.15.
with spectroscan table you most probably keep the lamp heated good enough by measuring printed target patch by patch in a quick succession - you can't do the same manually with SG...
whether standard calibration helps or not like the heating request - I think we can do the test... say execute calibration every 10th (or may be even every other) measurement... I need to dig out my Spectrolino... what is clear though that you can't calibrate once before measuring the whole big target
Why cannot I do the same manually with SG? Not as fast but not far enough
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Why cannot I do the same manually with SG? Not as fast but not far enough
does it work (as "fast" as strip reading by sliding spectrometer manually over printed target via ruler) with non flat targets (SG patches are sunken) ? I do not have the table, so may be I am wrong...
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That one - and it shows b* drift of 0.15
rather 0.2, albeit you certainly refer to subset corresponding to ~140 measurements... in any case need to test with frequent calibration and post the results
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does it work (as "fast" as strip reading by sliding spectrometer manually over printed target via ruler) with non flat targets (SG patches are sunken) ? I do not have the table, so may be I am wrong...
Spot metering stand is good help. But then again I think it is fast enough for lamp not to cool down substantially. The hand gets tired quite quickly though from repetitive movements.
I have not done such experiments but it would be interesting to measure at what point with regular measurements the lamp deposits start affecting measurements after initial reversing cycle.
Perhaps for Spectrolino the recycling procedure could be to perform several white patch calibrations one after the other in immediate succession - this could keep lamp sufficiently hot.
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and how do you keep reheating the lamp there (in the said spectrolino) to deal with tungsten deposits while measuring the target like SG ?
In my experience, the Spectrolino doesn't suffer from this problem anywhere near as much as the i1pro, since it doesn't support scanning. It always measures one patch at a time.
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for i1Pro* there are API calls (or workarounds) to instruct the spectrometer to heat its lamp from software on demand
Note that AFAIK such API calls are nothing to do with normal measurements, but a means of "fixing" or improving the lamp behavior by reconditioning it.
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I dusted off one of my spectrolinos and did the following with argyll v1.9.2 spotread tool : 5 times calibration -> 10 times reading -> 5 times calibration -> 10 times reading ... 80 measurements total, the spectrometer was sitting on the same spot on calibration tile (not moved at all)
(https://s26.postimg.org/hdad25ilj/spectrolino_1.jpg)
Reading X Y Z L* a* b*
1 85.782234 89.270920 72.694244 95.693524 -0.546974 0.828021
2 85.732605 89.218460 72.638466 95.671641 -0.545408 0.839347
3 85.707062 89.189056 72.607353 95.659371 -0.540278 0.845566
4 85.703644 89.187531 72.593620 95.658735 -0.543924 0.856553
5 85.693840 89.176422 72.586769 95.654099 -0.542273 0.854590
6 85.678612 89.158691 72.570488 95.646698 -0.538852 0.856161
7 85.689240 89.175812 72.576691 95.653844 -0.549778 0.863021
8 85.698586 89.177330 72.589737 95.654478 -0.535033 0.852631
9 85.698601 89.181488 72.585709 95.656213 -0.542484 0.859169
10 85.714172 89.194771 72.603287 95.661756 -0.537262 0.853256
11 85.683449 89.163841 72.575333 95.648848 -0.539071 0.855603
12 85.712059 89.197632 72.607452 95.662950 -0.546359 0.851649
13 85.708366 89.192856 72.600983 95.660957 -0.544673 0.853906
14 85.693832 89.175499 72.586792 95.653714 -0.540627 0.853906
15 85.704964 89.187416 72.594650 95.658687 -0.541250 0.855565
16 85.707382 89.190483 72.592903 95.659967 -0.542245 0.859309
17 85.706573 89.187775 72.591675 95.658837 -0.538885 0.858441
18 85.703850 89.187607 72.596313 95.658767 -0.543676 0.854238
19 85.697723 89.185097 72.596695 95.657719 -0.550616 0.852096
20 85.708412 89.185654 72.584885 95.657951 -0.531632 0.862891
21 85.729706 89.214485 72.634346 95.669982 -0.543679 0.840112
22 85.709106 89.198685 72.605621 95.663389 -0.553773 0.854018
23 85.730202 89.222290 72.633629 95.673239 -0.556788 0.846357
24 85.713455 89.193481 72.601097 95.661218 -0.536283 0.854255
25 85.702438 89.189613 72.590149 95.659604 -0.549924 0.861107
26 85.705643 89.188835 72.591309 95.659279 -0.542533 0.859527
27 85.725143 89.210869 72.620811 95.668473 -0.545704 0.849418
28 85.728348 89.213715 72.616600 95.669661 -0.544832 0.855170
29 85.737823 89.222916 72.626541 95.673500 -0.543665 0.853042
30 85.714668 89.199120 72.604935 95.663571 -0.544156 0.854935
31 85.650703 89.128616 72.529465 95.634143 -0.536934 0.870631
32 85.703850 89.187912 72.594421 95.658894 -0.544225 0.856123
33 85.720634 89.203072 72.606575 95.665220 -0.540110 0.856335
34 85.719208 89.207253 72.600479 95.666964 -0.550297 0.864707
35 85.716835 89.203674 72.600616 95.665471 -0.548298 0.862012
36 85.713715 89.198341 72.601585 95.663246 -0.544540 0.857322
37 85.718925 89.202591 72.602356 95.665019 -0.542441 0.859701
38 85.714989 89.200294 72.600601 95.664061 -0.545671 0.859593
39 85.701889 89.182816 72.579147 95.656767 -0.538723 0.865899
40 85.727394 89.211311 72.609596 95.668658 -0.542293 0.859604
41 85.629387 89.107620 72.510094 95.625377 -0.539024 0.872576
42 85.700348 89.185783 72.588676 95.658006 -0.546944 0.859647
43 85.724167 89.208954 72.618019 95.667674 -0.544086 0.850497
44 85.711777 89.195641 72.611778 95.662119 -0.543305 0.846410
45 85.707283 89.190392 72.598167 95.659929 -0.542266 0.854610
46 85.705742 89.192657 72.593376 95.660874 -0.549223 0.860457
47 85.705307 89.188721 72.598358 95.659231 -0.542955 0.853240
48 85.702141 89.186234 72.586517 95.658193 -0.544401 0.861871
49 85.701561 89.188057 72.580666 95.658954 -0.548765 0.868334
50 85.715836 89.200142 72.598305 95.663997 -0.543813 0.861505
51 85.709808 89.191994 72.606186 95.660597 -0.540426 0.848707
52 85.703339 89.187737 72.595146 95.658821 -0.544865 0.855359
53 85.765541 89.251625 72.672592 95.685476 -0.543481 0.833185
54 85.706375 89.191055 72.594757 95.660206 -0.545157 0.858089
55 85.682381 89.164925 72.570137 95.649300 -0.543018 0.860956
56 85.695488 89.176414 72.579582 95.654096 -0.539178 0.860910
57 85.710899 89.195717 72.593719 95.662151 -0.545083 0.862356
58 85.702850 89.184631 72.586922 95.657525 -0.540192 0.860363
59 85.697563 89.181999 72.582603 95.656426 -0.545344 0.862269
60 85.698921 89.182152 72.576904 95.656490 -0.543079 0.867395
61 85.625984 89.102379 72.508705 95.623188 -0.535957 0.870025
62 85.698807 89.179634 72.585548 95.655439 -0.538764 0.857976
63 85.710556 89.191566 72.600319 95.660419 -0.538259 0.853562
64 85.698288 89.176720 72.589828 95.654223 -0.534491 0.852112
65 85.693253 89.173920 72.578049 95.653054 -0.538870 0.860465
66 85.693466 89.170570 72.586960 95.651656 -0.532445 0.850211
67 85.692780 89.175224 72.575790 95.653599 -0.542101 0.863391
68 85.694450 89.179749 72.576675 95.655487 -0.547116 0.865868
69 85.694061 89.168251 72.580711 95.650688 -0.527160 0.854042
70 85.706253 89.188446 72.593971 95.659117 -0.540692 0.856903
71 85.700050 89.181068 72.600708 95.656038 -0.539019 0.845666
72 85.699860 89.181961 72.594864 95.656410 -0.540981 0.851452
73 85.690910 89.170486 72.583107 95.651621 -0.537073 0.853542
74 85.689316 89.170753 72.578285 95.651733 -0.540535 0.857978
75 85.708305 89.189537 72.606316 95.659572 -0.538817 0.846825
76 85.690689 89.171219 72.582169 95.651927 -0.538805 0.854895
77 85.680473 89.160133 72.558098 95.647300 -0.537965 0.868105
78 85.694283 89.179855 72.581009 95.655532 -0.547622 0.862130
79 85.690201 89.165680 72.576309 95.649615 -0.529753 0.856066
80 85.687149 89.162430 72.575684 95.648259 -0.529612 0.854278
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seems there is no drift then... at least with constant calibration
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Looks like I created a monster! 8)
D.
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I use this FAGDI recommendation. It is essential to know its onw values.
http://www.imagescienceassociates.com/mm5/pubs/KenFleisher-Optimizing_Conformance_to_FADGI_and_Metamorfoze_v3.pptx
Slides and comments from slide 9 to slide 16
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Very interesting.
Thanks for sharing. ;)
D.