Re: physical colors and Mathematica colors

• To: mathgroup at smc.vnet.net
• Subject: [mg26414] Re: physical colors and Mathematica colors
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Wed, 20 Dec 2000 00:21:37 -0500 (EST)
• Organization: Universitaet Leipzig
• References: <91f7u4\$55k@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

a) the conversion in a nice FORTRAN program can be found at
http://www.physics.sfasu.edu/astro/color.html
b) You can dwonload a Mathematica package
ColorFuntions.m form

http://phong.informatik.uni-leipzig.de/~kuska/visualsupp/ColorFunctions.m

with a function SpectralColor[h] that returns the RGB colors for
h in [0,1] (or lambda in [380,700] nm)
the scalung for h in [0,1] is done to use it as value for the
ColorFunction option.

Regards
Jens

PNichols at cornell-iowa.edu 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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