RE: Color accuracy in copying paintings
RE: Color accuracy in copying paintings
- Subject: RE: Color accuracy in copying paintings
- From: Ray Maxwell <email@hidden>
- Date: Mon, 22 Jul 2002 09:26:16 -0700
Sorry to disagree, but there are no RGB based reflected light pigment
systems.
If you put down a red pigment on paper it will absorb all wavelengths of
light except red, which it reflects. Now add a green pigment...it will
absorb all wavelengths of light except green. If red absorbs green and blue
and green absorbs red and blue you now have no light reflected. You now
have black. While you can put down pigments with red, blue, and green
reflectance, you cannot produce a tristimulus reflected light system that
will reproduce a reasonable color gamut. If you put down any two of the RGB
pigments you get black.
I agree that the pigments used in oil painting are completely different than
the CMY dyes used in films. However, you cannot characterized them as an
RGB pigment system.
Ray
Ray Maxwell
Senior Color Systems Engineer, Inkjet Printing
Creo Inc.
4225 Kincaid Street
Burnaby, B.C.
Canada V5G 4P5
Phone (604) 451-2700 ext. 2004
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From: Ernst Dinkla
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Sent: Saturday, July 20, 2002 2:05 PM
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To: email@hidden
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Subject: Re: Color accuracy in copying paintings
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>
----- Original Message -----
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From: "Terry Wyse" <email@hidden>
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To: "ColorSync User List" <email@hidden>
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Sent: Saturday, July 20, 2002 3:32 PM
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Subject: Re: Color accuracy in copying paintings
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>
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> on 7/20/02 4:27 AM, Tony Riley wrote:
>
>
>
> > I think the shortcomings in reproducing rgb pigments
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> > in paintings...
>
>
>
> There's no such thing as RGB pigments. RGB is additive color,
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CMY is
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> subtractive. To put another way, RGB is light and CMY is
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pigment/paint/dye.
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>
>
> Of course, I could be wrong. :-)
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>
There are RGB pigments, dyes, phosphors and I guess even other
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colorants. Problem is you need a lot of light to get an additive
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RGB system of colourmixing working. Monitor and television CRT's
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are the best examples of RGB additive mixing. Lumiere's
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Autochrome, early Agfachrome, Finlay etc slide films showed that
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RGB additive mixing was possible and the first was a commercial
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success. Polaroid did some attempts to bring additive RGB film
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back as an instant 8 mm movie / 35 mm slide film. All those
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systems used dyes though with their higher transparency. The
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difference between RGB and CMY colourmixing is that the first has
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to be additive and the second subtractive and the first needs a
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lot more light than the second.
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>
Ernst
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