Re: physical colors and Mathematica colors

• To: mathgroup at smc.vnet.net
• Subject: [mg26406] Re: [mg26392] physical colors and Mathematica colors
• From: Ben Jacobson <bjacobson at illumitech.com>
• Date: Wed, 20 Dec 2000 00:21:31 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Hello Preston,

If you just need to display the approximate color in Mathematica, the
function Hue[] will get you most of the way there.  See the help
documentation and "Section 2.9.17 Advanced Topic: Color Output" in The
Mathematica Book.

If you need the actual equations, life will be more complicated.  You
should be able to calculate the CIE illuminants X, Y, and Z as integrals
over the spectrum, and then convert them to various RGB or other values.
Check out the excellent reference at
http://vera.inforamp.net/~poynton/notes/colour_and_gamma/ColorFAQ.html

Ben Jacobson
Illumitech Inc.
http://www.illumitech.com

At 02:40 AM 12/16/00 -0500, Preston Nichols wrote:
>Dear Group,
>
>I am working on a package for which I need a function which takes a
>wavelength of light (in nanometers, for example) and returns an RGBColor
>specification.  Has anyone made such a function for Mathematica?
>
>Of course, it is not essential that the result be RGBColor; any other
>standard computer-graphics color model would do the job (HSB, HLS, CMY,
>CMYK, etc.), because the conversions are standard.  It's only the conversion
>between one of these and physical wavelengths which I don't know.
>
>I understand that human color perception is a complicated matter, and so is
>rendering of color on computer display devices.  (The brightness dimension
>is perhaps the most obvious ambiguity.)  It's probably nonsense  to ask for
>a "perfect" correspondence between wavelength and RGB.  But is there a
>"standard" mapping?  Or one that you think is "pretty good"?
>
>I shall be grateful for even the smallest suggestions.
>
>
>Preston Nichols
>Visiting Assistant Professor of Mathematics
>Cornell College
>
>
>

```

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