Re: Colormatch vs Adobe 98
Re: Colormatch vs Adobe 98
- Subject: Re: Colormatch vs Adobe 98
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Fri, 01 Feb 2002 15:57:12 -0600
Chris Murphy wrote:
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Would it be correct to say that an emissive colorimeter also has a
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reference illuminant, but that it's based on the SPD of a CRT (or LCD, or
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somehow can switch between both) instead of D50 or D65 - and that this
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component is built into the selection of the specific filters for the
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colorimeter and the math used to put an XYZ number to the stimulus they
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measure?
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As a colorimeter doesn't see the spectral emission from a monitor, it
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doesn't have any way to utilize an illuminant SPD; but there is still
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effectively an "implied" illuminant which is the spectral characteristics
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of the display itself - which is why colorimeters for CRTs don't do a
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good job on LCD's. They must be specifically designed with those spectral
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emissions in mind.
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Yes/No?
First of all, I think we might get a more authoritative response from
someone in that business, for example Raymond Cheydleur at X-Rite.
But just as finding "real-world" light sources that match the SPD of D50 is
difficult, I think it is also difficult to come up with colorimeter sensors
and filters that closely match the CIE standard observer functions. But in a
*restricted* application (such as building an instrument that measures only
CRT monitors), the system may be "tuned" based on a priori information about
CRT phosphors in general. Such a tuned approximation may prove quite good
when actually measuring a CRT, but may fail when measuring something else,
such as an LCD display.
But regardless, this should not be thought of as a "reference illuminant" in
the sense that that term is used with D50, D65, etc. (at least IMO).
--
Bruce J. Lindbloom
www.brucelindbloom.com