Re: Epson 5500 Metamerism
Re: Epson 5500 Metamerism
- Subject: Re: Epson 5500 Metamerism
- From: Dan Reid <email@hidden>
- Date: Fri, 31 Aug 2001 13:18:57 -0600
On Thu, 30 Aug 2001 19:53:57 -0400, Scott Gregory <email@hidden> wrote:
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snip -
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The problem today is there is no easy and accurate method for factoring in
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the actual illuminant that the media you are profiling is being viewed
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under. Most profiling applications use the spectral power distribution of
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D50 to calculate the tristimulus values and the subsequent LAB's, not an
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illuminant close to the actual viewing condition. This won't reduce a
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media's susceptibility to metamerisms but it does enable matching under
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different illuminants. Knowing the characteristics of the ultimate viewing
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condition is essential to communicating the correct color.
Then you would have to have different profiles for each viewing environment.
A beast to administrate and ensure the *correct* profile is being applied on
output *if* you know final condition, which most of the time the print
provider does not. Hence, that's why the ISO body agreed to use D50 as
viewing illuminant to not consider final viewing conditions.
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Getting the correct amount of UV factored in can also be important but more
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times then not using the wrong illuminant in your spectral integrations will
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lead to much larger errors.
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That's the problem we face today. Depending on how different your viewing
illuminant is from D50 will have a profound impact on the color tonality
since color matching is happening under D50.
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snip
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The ICC has a viewingConditionsType tag which is a start IF profile building
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vendors and profile applications used it. The tag does fall short of
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actually communicating the viewing illuminant spectrum and some dye
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characteristic information. This could be used to at least do a first order
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compensation for the effect of different illuminants.
Excellent point! I totally agree vendors should start offering this option
in their packages. But then again I would also like Named Color Profiles
supported in RIPs and Color Servers. Patience is a virtue.
--
Dan B. Reid
RENAISSANCE PHOTOGRAPHIC IMAGING
Color Imaging Solutions Provider
http://www.rpimaging.com | email@hidden
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