[argyllcms] Re: How do I force dispcal to always map R0 B0 G0 -> R0 B0 G0 on the calibrated video LUT?
- From: Alexander <adfirestone@xxxxxxxxx>
- To: argyllcms <argyllcms@xxxxxxxxxxxxx>
- Date: Tue, 12 Jan 2010 07:31:01 -0800
On Sun, Dec 20, 2009 at 5:21 PM, Alexander <adfirestone@xxxxxxxxx> wrote:
> Are there any settings for dispcal I can set to always map R0 B0 G0 >
> R0 B0 G0 (or possibly something close to black like R0 G100 B72) and
> then create the desired gamma curve based off that?
>
> Reading though the manual it seems like it may have something to do
> with the -f or -k parameters but the descriptions confuse me a bit.
>
> The problem arises where if try to make a profile with very very dark
> black (monitor black reads as 0.00cdm2), I have an issue with Argyll
> always mapping R0 B0 G0 to something like R1985 B2125 G2251 which
> changes my 0.00cdm2 black into a ~0.05-0.10cdm2 black. When I set my
> CRT to a very very dark black for night viewing, I want to keep that
> very very dark black after calibration.
>
> By taking the video lut curve generated by Argyll, editing the black
> point in BasICColor, end then making slight adjustment to the curve in
> BasICColor while checking back and forth with ColorHFCR until I get
> the correct gamma curve, I have been able to get the results I want. I
> just hope there is some easier way that I have overlooked as the
> former is a pain and takes a bit of time to get right.
>
> Any suggested settings to try?
>
> Thank you.
>
I appear to have found a simple solution to this problem.
After calibration is finished, dispcal scales and then applies the VideoLUT
values it generated. The scaled values have the problem of black being
mapped to some brighter non-black value which I was originally complaining
about. R0 G0 B0 is mapped to R3614 G2285 B2055
I discovered that (at least in RC4) dispcal stores the unscaled VideoLUT
values in the .cal file. This is good news, since the unscaled values are
exactly what I want. R0 G0 B0 is mapped to R60 G468 B0.
So immediatly after running dispcal, I would then run dispread to create a
bright.ti3 with the scaled VideoLUT values.
Afterwords I would run dispread with the -k parameter pointing to my .cal
file which will create a dark.ti3 with the unscaled VideoLUT values
contained in the .cal file.
Then with colprof I can create scaled ICC profiles with the bright.ti3 and
unscaled ICC profiles with the dark.ti3.
Graeme, can you explain the difference between the scaled and unscaled
VideoLUT values? What is the purpose of dispcal scaling the values at the
final step?
Would there be a reason not to use the unscaled values contained in the .cal
file? Both appear to have my specified gamma (unscaled is closer), and both
are close to my desired color temperature (unscaled is slightly low and
scaled is slightly high) with low dE values.
__________
First 16 scaled VideoLUT values:
0.0000 0.055146 0.034867 0.031357
3.9216e-003 0.061036 0.041764 0.038437
7.8431e-003 0.067063 0.048966 0.045716
0.011765 0.073243 0.056519 0.053178
0.015686 0.079561 0.064439 0.060868
0.019608 0.086046 0.072740 0.068772
0.023529 0.092729 0.081407 0.077043
0.027451 0.099748 0.090700 0.085863
0.031373 0.10716 0.10063 0.095293
0.035294 0.11490 0.11104 0.10513
0.039216 0.12279 0.12152 0.11502
0.043137 0.13059 0.13149 0.12459
0.047059 0.13805 0.14052 0.13352
0.050980 0.14505 0.14853 0.14173
0.054902 0.15154 0.15566 0.14932
0.058824 0.15760 0.16208 0.15639
0 3614 2285 2055
1 4000 2737 2519
2 4395 3209 2996
3 4800 3704 3485
4 5214 4223 3989
5 5639 4767 4507
6 6077 5335 5049
7 6537 5944 5627
8 7023 6595 6245
9 7530 7277 6890
10 8047 7964 7538
11 8558 8617 8165
12 9047 9209 8750
13 9506 9734 9288
14 9931 10201 9786
15 10328 10622 10249
16 10703 11010 10683
__________
Last 16 scaled VideoLUT values:
0.94118 0.94833 0.94795 0.95064
0.94510 0.95154 0.95114 0.95378
0.94902 0.95471 0.95435 0.95695
0.95294 0.95789 0.95756 0.96013
0.95686 0.96104 0.96080 0.96333
0.96078 0.96419 0.96405 0.96655
0.96471 0.96735 0.96733 0.96979
0.96863 0.97049 0.97063 0.97304
0.97255 0.97363 0.97394 0.97629
0.97647 0.97679 0.97726 0.97957
0.98039 0.97995 0.98061 0.98286
0.98431 0.98309 0.98396 0.98619
0.98824 0.98625 0.98735 0.98952
0.99216 0.98939 0.99075 0.99287
0.99608 0.99255 0.99417 0.99623
1.0000 0.99571 0.99760 0.99960
240 62149 62124 62300
241 62359 62333 62506
242 62567 62543 62714
243 62775 62754 62922
244 62982 62966 63132
245 63188 63179 63343
246 63395 63394 63555
247 63601 63610 63768
248 63807 63827 63981
249 64014 64045 64196
250 64221 64264 64412
251 64427 64484 64630
252 64634 64706 64848
253 64840 64929 65068
254 65047 65153 65288
255 65254 65378 65509
__________
First 16 unscaled VideoLUT values:
0.0000 9.1554e-004 7.1412e-003 0.0000
3.9216e-003 4.1352e-003 0.011841 3.6622e-004
7.8431e-003 7.7821e-003 0.017670 7.7974e-003
0.011765 0.011978 0.025025 0.016480
0.015686 0.016831 0.034668 0.026734
0.019608 0.022492 0.047623 0.038758
0.023529 0.029221 0.061891 0.051026
0.027451 0.037339 0.073854 0.062043
0.031373 0.047425 0.083253 0.071595
0.035294 0.059648 0.091386 0.080308
0.039216 0.073198 0.099290 0.088838
0.043137 0.086549 0.10765 0.097734
0.047059 0.099016 0.11681 0.10721
0.050980 0.11066 0.12654 0.11714
0.054902 0.12180 0.13635 0.12723
0.058824 0.13249 0.14562 0.13703
0 60 468 0
1 271 776 24
2 510 1158 511
3 785 1640 1080
4 1103 2272 1752
5 1474 3121 2540
6 1915 4056 3344
7 2447 4840 4066
8 3108 5456 4692
9 3909 5989 5263
10 4797 6507 5822
11 5672 7055 6405
12 6489 7655 7026
13 7252 8293 7677
14 7982 8936 8338
15 8683 9543 8980
16 9346 10107 9586
__________
Last 16 unscaled VideoLUT values:
0.94118 0.95261 0.94980 0.94850
0.94510 0.95583 0.95309 0.95187
0.94902 0.95904 0.95639 0.95525
0.95294 0.96223 0.95970 0.95865
0.95686 0.96541 0.96303 0.96205
0.96078 0.96860 0.96635 0.96545
0.96471 0.97179 0.96971 0.96883
0.96863 0.97498 0.97307 0.97221
0.97255 0.97818 0.97644 0.97556
0.97647 0.98140 0.97983 0.97891
0.98039 0.98462 0.98322 0.98224
0.98431 0.98785 0.98660 0.98555
0.98824 0.99110 0.99001 0.98885
0.99216 0.99435 0.99342 0.99214
0.99608 0.99760 0.99684 0.99541
1.0000 1.0000 1.0000 0.99867
240 62429 62245 62160
241 62640 62461 62381
242 62851 62677 62602
243 63060 62894 62825
244 63268 63112 63048
245 63477 63330 63271
246 63686 63550 63492
247 63895 63770 63714
248 64105 63991 63933
249 64316 64213 64153
250 64527 64435 64371
251 64739 64657 64588
252 64952 64880 64804
253 65165 65104 65020
254 65378 65328 65234
255 65535 65535 65448
__________
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