Re: Measurement temp/angle
Re: Measurement temp/angle
- Subject: Re: Measurement temp/angle
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Thu, 17 Jan 2002 09:51:21 -0600
Darren Sheppard wrote:
>
I have had some LAB measurements of liquid done. The liquid was measured at
>
D65/10deg, will this have any affect on the results when the values are
>
converted to a RGB output profile which I believe was measured at D50/45deg?
I guess no one else is going to respond to this question, so I'll try.
Short answer: Yes.
Long answer: You have measurements made WRT D65, 10 degree standard
observer. You need measurements WRT D50, 2 degree standard observer in order
to use them properly with the profile. Simply plugging in your measurements
will cause errors due to the mismatched reference whites and standard
observers. This error is probably significant, for example, using the
ColorChecker calculator on my web site you can see that the "Blue" patch has
these two measurements:
D65, 10 Degree: Lab = 32.30 15.04 -47.77
D50, 2 Degree: Lab = 28.77 18.89 -53.79
These two are different from each other by about 8 delta E. Note that the
differences are seen in all three color components. Adaptation algorithms
may be used to "predict" D50 values from D65 values (this will be an
approximation, though), but I am not aware of any methods to predict 2
degree from 10 degree. Maybe someone else knows (Phil Green?).
--
Bruce J. Lindbloom
www.brucelindbloom.com