Color

[P3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Fri, 23 May 1997 11:31:04 -0500
>From: P3D Jim Crowell  <crowell@xxxxxxxxxxxxxxx>
>Subject: Re: New Fuji Film: Astia

>At 6:31 AM -0700 5/23/97, P3D John W Roberts wrote:
>>
>>Barring any wildly futuristic stuff, any color can be completely described
>>by its frequency spectrum. Color theory maps the range of all possible colors
>>that a human can see into a bounded object in a 2-dimensional space. The
>>points along the periphery of that object (well, most of it) represent pure
>>wavelengths of visible light. Any perceptible color (represented by a point)
>>within the interior of that object can be replicated by any of an infinite
>>number of combinations of two or more wavelengths.

>3 or more wavelengths, actually...

What I meant to say is that for a given (x,y) or (u',v') point in the
chromaticity diagram that's not on the periphery of the diagram, there are
an infinite number of pairs of pure wavelengths, which if blended in the
appropriate relative amounts, will match the color at that point. For example,
a certain mix of (approximately) 580nm and 475nm will produce what looks to
the eye like pure white, and a mix of ~630nm and ~495nm could do the same.
(That's going by a 1982 version of the x-y diagram - I don't have a copy of
the u'v' diagram.)

I think what you're describing is that if you can put out light at 3 (or more)
points in the color space (for instance corresponding to monochromatic
sources or phosphors), then you can match any color within the triangle
(polygon) defined by those points, by proper adjustment of the relative
intensities.

Is that a correct interpretation?

>the 3d dimension is luminance...

Agreed.

Any recommendations on a beginner-level or intermediate text for color theory?

Thanks.
John R


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