I am working on a project where I create 3D printed reproductions of paintings,
using 2 Nikon D800E cameras, for which I need an ICC profile. For this purpose
I bought a custom 'Artist Paint Target', which is developed by prof. Roy Berns,
which should be more suitable for painting reproduction than for instance the
ColorChecker. According to his research specific pigments used in paintings
should be better distinguishable with this target.
I have one question regarding the PSC values in the .ti3 file. I have L a* b*
reference values for this target. (Nominal Colorimetric L*a*b* data for the
Artist Paint Target: CIE illuminant D50 and the 1931 standard observer) If I
input these values in the .ti3 file (I change this text file manually), the
colprof function just fails at the very beginning, saying that I have too many
data rows (25 or 26 instead of 24), even though this is definitely not the
case. Does anybody else have experience with this? Am I making some mistake or
is it a bug of some kind?!
As an alternative, I have converted the L a* b* values to XYZ using Matlab
(using the D50 illuminant).
Info in Matlab: CIE standard illuminant D50, [0.9642, 1.0000, 0.8251]
Could anybody confirm that this should lead to the right result.
I could also enter the spectral reference data from the target, this is also
provided in the reference document. Would this make a difference for the end
result? Is there anybody with a a sample .ti3 file for this, that I could adapt?
Another question: if I were to combine reference and measured values from the
Colorchecker DS with the custom target into one .ti3 file, should this (in
theory) lead to a better result?
This is the text in the .ti3 file for the Lab values:
CTI3
DESCRIPTOR "Argyll Calibration Target chart information 3"
ORIGINATOR "Argyll target"
CREATED "Tue Dec 19 22:00:00 2017”
KEYWORD "DEVICE_CLASS"
DEVICE_CLASS "INPUT"
KEYWORD "COLOR_REP"
COLOR_REP “LAB_RGB"
NUMBER_OF_FIELDS 7
BEGIN_DATA_FORMAT
SAMPLE_ID LAB_L LAB_A LAB_B RGB_R RGB_G RGB_B
END_DATA_FORMAT
NUMBER_OF_SETS 24
BEGIN_DATA
A1 42.07 14.07 -57.19 0.363325653015404 0.991573903438153 10.1964396511307
A2 61.37 -47.75 39.35 3.43998957971003 7.93156276001316 0.501748912762064
A3 46.37 54.01 -5.07 4.54794557594653 0.227276735550572 2.94783744452663
A4 97.67 -0.56 1.33 20.1330886809756 20.6167589954952 19.0595380933726
B1 45.59 4.29 -52.39 0.495628117949237 1.70977732328425 10.7192357230311
B2 71.36 -32.81 71.21 7.55163028694856 11.6130286924037 0.000504670903556457
B3 46.85 31.79 -25.75 3.12145797416093 0.992614030164133 5.62573480543184
B4 77.52 -0.03 0.45 10.5387819823025 10.7716220472923 10.1837461364526
C1 45.93 -15.15 -44.75 0.100429305997803 2.2035604572445 9.20842854346531
C2 87.93 6.14 97.92 19.1123959033958 15.9006372385818 0.000334705299450423
C3 46.81 23.42 -37.83 2.14657144322642 1.25607339921692 7.73733784133839
C4 57.52 -0.16 0.15 4.48982958254916 4.60408843509735 4.34795388899375
D1 50.85 -36.91 -21.19 0.733441895177516 3.91087311028085 6.56242380505373
D2 75.27 36.03 80.97 16.9241269244714 6.94007172598058 0.000402444076343195
D3 84.78 2.31 15.52 14.7592958416836 13.9282276783856 9.43705118210677
D4 37.20 0.16 0.52 1.15489902034883 1.15570670698395 1.07545024139091
E1 53.54 -48.53 -2.65 1.13874240664862 5.05306614056779 4.50046722977704
E2 65.54 55.35 66.57 14.0567278858887 2.72200920980583 0.0148128445270806
E3 62.64 20.55 21.17 7.69445350140996 4.67349557960025 2.69222270986213
E4 21.88 -0.05 -0.23 0.0406130154927572 0.0530280286108541 0.0573865014907212
F1 59.42 -57.33 18.70 2.20352600735343 7.18197643423707 3.17374143265111
F2 48.44 62.31 30.74 5.95756469910468 0.0553143138540674 0.474459591675886
F3 39.40 15.60 14.69 1.77568279659772 0.817988075814209 0.37441604393231
F4 10.41 0.45 1.18 0.0153040727475023 0.0214548104792169 0.0276769646923521
END_DATA
Cheers,
Willemijn Elkhuizen
