ColorChecker Digital SG - Which patch to use to create a White Balance?

[scyth]

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

[Alexey.Danilchenko]

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.

[GWGill]

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.

[GWGill]

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.

[scyth]

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)



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

-------------------------

seems there is no drift then... at least with constant calibration

[Dinarius]

Looks like I created a monster! 

D.

[photocor]

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

[Dinarius]

Very interesting.

Thanks for sharing. 

D.