[comp.graphics] Fequency

ccoprrm@pyr.gatech.EDU (ROBERT E. MINSK) (06/27/89)

  Does anyone have a program or know of an algorithm to convert from
Frequency (or wavelength) to CIE XYZ coordinate space.  I am not looking
for CIE to RGB or for manipulations within the color space; this I 
already know how to do.

-- 
ROBERT E. MINSK
Georgia Insitute of Technology, Atlanta Georgia, 30332
uucp: ...!{akgua,allegra,amd,hplabs,ihnp4,seismo,ut-ngp}!gatech!gitpyr!ccoprrm
ARPA: ccoprrm@pyr.gatech.edu

bdb@becker.UUCP (Bruce Becker) (06/28/89)

In article <8594@pyr.gatech.EDU> ccoprrm@pyr.gatech.edu.UUCP (ROBERT E. MINSK) writes:
|
|  Does anyone have a program or know of an algorithm to convert from
|Frequency (or wavelength) to CIE XYZ coordinate space.  I am not looking
|for CIE to RGB or for manipulations within the color space; this I 
|already know how to do.

	This is off the top of my head, so it will need some
	refinement...

	Tables exist in several places which map the periphery
	of the CIE standard visibility gamut in 5-nanometer
	increments (or sometimes other resolutions), expressed
	in CIE coordinates.
	Given this polygon, you can interpolate the wavelength
	into its border so as to arrive at the fully saturated
	CIE coordinate value. Other saturations occur monotonically
	on a line from there to the current reference white point.
	The transformation from the (x,y,Y) coordinate system
	(if needed), to (X,Y,Z) is simple.

Cheers,
-- 
   __	 Bruce Becker	Toronto, Ont.
w \cc/	 Internet: bdb@becker.UUCP, bruce@gpu.utcs.toronto.edu
 `/v/-e	 BitNet:   BECKER@HUMBER.BITNET
_<  >_	 "Not only am I the Nair Club president, I'm also a client" - Y. Brynner

jlg@hpfcdq.HP.COM (Jeff Gerckens) (07/06/89)

> In article <8594@pyr.gatech.EDU> ccoprrm@pyr.gatech.edu.UUCP (ROBERT E. MINSK) writes:
> |
> |   Does anyone have a program or know of an algorithm to convert from
> |Frequency (or wavelength) to CIE XYZ coordinate space.  I am not looking
> |for CIE to RGB or for manipulations within the color space; this I 
> |already know how to do.
> 
> This is off the top of my head, so it will need some
> refinement...
> 
> Tables exist in several places which map the periphery
> of the CIE standard visibility gamut in 5-nanometer
> increments (or sometimes other resolutions), expressed
> in CIE coordinates.
> Given this polygon, you can interpolate the wavelength
> into its border so as to arrive at the fully saturated
> CIE coordinate value. Other saturations occur monotonically
> on a line from there to the current reference white point.
> The transformation from the (x,y,Y) coordinate system
> (if needed), to (X,Y,Z) is simple.

Tables can be found in :

   Color in Business, Science, and Industry by Deanne Judd,

and 

   Color Science: Concepts and Methods, Quantitative Data and
   Formulae by Wyszecki and Stiles

- Jeff Gerckens, Graphics Technology Division, Hewlett-Packard
  jlg%hpfcrg.fc.hp@hplabs.hp.com