Re: Optical
Re: Optical
- Subject: Re: Optical
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Sat, 30 Mar 2002 09:12:07 -0600
Shiloh Burton wrote:
>
I thought D65 and 6500K were interchangeable. Yet, when I toggle back and
>
forth between the two when in optical there is a signifcant difference.
>
6500 K is much warmer and/or red than D65. What is the reason for this? Can
>
someone please explain to me the difference between the two?
I have three comments on this (none of which have to do with Optical,
sorry):
a) D65 is specified as a particular set of XYZ values. From Wyszecki and
Stiles, page 771, D65 is XYZ = 0.95017, 1.00000, 1.08813. This has a
correlated color temperature that is ever so slightly higher than 6500K
(insignificant in terms of the question asked).
b) The spectra of "D" illuminants are calculated from correlated color
temperatures, and these spectra are "ragged" in appearance.
c) The spectra of blackbody radiators are calculated from color
temperatures, and are smooth in appearance, but have the same general shape
(broadly speaking) as the corresponding D illuminant spectra.
I have a "CIE Spectral Display" calculator on the "Color" page my web site
<
http://www.brucelindbloom.com> that graphs out the above spectra (and many
others) so you can compare them for yourself.
No matter what the case with Optical, I would not expect a significant
difference between D65 and 6500K. I'll leave speculation to others more
familiar with that product.
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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