Re: Color accuracy in copying paintings
Re: Color accuracy in copying paintings
- Subject: Re: Color accuracy in copying paintings
- From: "Ernst Dinkla" <email@hidden>
- Date: Mon, 22 Jul 2002 12:02:12 +0200
----- Original Message -----
From: "Ray Maxwell" <email@hidden>
To: <email@hidden>
Cc: "'Ernst Dinkla'" <email@hidden>
Sent: Monday, July 22, 2002 6:26 PM
Subject: RE: Color accuracy in copying paintings
>
Sorry to disagree, but there are no RGB based reflected light pigment
>
systems.
I agree on "no practical (additive) RGB based reflecting light pigment (and
dye) systems"
You need a lot of light to go through one layer of R or G or B get it
reflected from the substrate and again through the layer and still keep
enough brilliance. Then it isn't easy to print very small lines or dots of R
or G or B next to one another.
Yet there are nice physical experiments with rotating discs divided in three
parts RGB that show a not really white but yellow/grey disc. Proof that
reflected additive RGB mixing is possible in a way.
>
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.
RGB colours need additive mixing, additive mixing needs RGB colours.
I don't think I made that mistake in my message.
>
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.
I didn't characterize oil painting as an RGB pigment system. Though a nice
pointilistic painting made of RGB dots only, all next to one another and
with a lot of light thrown through it from the back might make it clear that
additive RGB pigment colourmixing is possible.
>
>
Ray
>
>
Ray Maxwell
>
Senior Color Systems Engineer, Inkjet Printing
>
Creo Inc.
>
4225 Kincaid Street
>
Burnaby, B.C.
>
Canada V5G 4P5
Ernst
Local silkscreen and digital inkjet printer.
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