Re: Reference File for Gretag Macbeth Color Checker Chart
Re: Reference File for Gretag Macbeth Color Checker Chart
- Subject: Re: Reference File for Gretag Macbeth Color Checker Chart
- From: Robin Myers <email@hidden>
- Date: Tue, 19 Mar 2002 10:00:13 -0800
- Organization: Robin Myers Imaging
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Date: Tue, 19 Mar 2002 07:58:31 -0800
From: Robin Myers <email@hidden>
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To: "Bruce J. Lindbloom" <email@hidden>
Subject: Re: Reference File for Gretag Macbeth Color Checker Chart
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Bruce,
>
Steven Kornreich wrote:
>
> Does anyone know where I can get the Reference file for the 24 patch Gretag
>
> Color Check chart?
>
>
As far as I know "the" Reference file doesn't exist. By that I mean there is
>
no "official" reference file for that chart. If anyone has information to
>
the contrary, please let me know. What would be even more useful would be
>
"official" spectral reflectance curves of these colors. I have searched for
>
these for years, but I don't think they exist, not even in the back room at
>
Macbeth.
I have communicated with several people at GretagMacbeth and Munsell, and some of their
ex-employees that have moved on but should be "in the know", and they all say that the
spectral data for the ColorChecker no longer exists. The only record of the data are the
graphs in the 1976 paper describing its development (sorry, I don't have the reference
handy).
In addition, I have measured 6 ColorCheckers of various ages and sometime in the last 10
years there appears to have been a formulation change with some of the colors. Spectral
measurements of my ColorCheckers from 11 years ago agree very closely with each other, my
3 year old and more recent ColorCheckers also agree with each other, but they do not
agree with the older ColorCheckers.
Also, the recent ColorChecker DC appears to be using a different binder than the older
ColorCheckers. The new binder has made many of the squares polarizing. This renders the
new ColorChecker DC useless in polarized or cross-polarized photographic situations (e.g.
fine art reproduction).
Regards,
Robin Myers
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