[argyllcms] Re: Question about colprof and black point
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 18 Nov 2010 08:47:19 +1100
Vittorio Villani wrote:
Creating rspl..
Fine tuning white and black point mapping
White is [...]
Black is 9,994558 0.850210 1.285811, should be 10.012171 0.988195 1.630301
What are the numbers of the balck about? 9,99 is the L* value or what?
They are Jab values (CICAM02).
My black point is (.ti2 file):
"Q3" 0.0000 0.0000 0.0000 1.0000 1.0000 1.000
The reading of this patch with the ColorMunki software gives me this result in
L*a*b* values:
L*=4.6
Using profcheck I get this result for the Q3 patch:
[0.219403] 5: 0.000000 0.000000 0.000000 -> 4.715842 1.202572 1.658739 should
be 4.812903 1.350490 1.624429
So I can't understand what is that black point about.
See above. There is an appearance conversion between D50 L*a*b* values and
the CIECAM02 Jab values, hence the difference. If you use xicclu -pj with the
appropriate viewing conditions set, you should get matching numbers.
Graeme Gill.
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