California State University, Long Beach
Giving white a place in the spectrum allows hues and values to be plotted on the same plane of color space. This chart of the hue/value relationships of color was created by mapping the hues of the RGB spectrum onto the values of the grayscale. The chart allows the selection of equal value color combinations similar to the harmonies of a traditional artist's color wheel, but in the far greater gamut of hues and values of RGB color, making color selection and matching more intuitive for the general computer user.
For more information, please read the following paper on White is Green that was presented at the International Association of Color AIC Color 97 in Kyoto, Japan in May of 1997.
Please also see additional arguments for "White is Green" as well as the Percept Color Wheel presented at Electronic Imaging '99 San Jose, California, January 1999.
The most recent paper is White is Green - New Schematic Diagrams (PDF format) Presented at AIC Color 2001 in Rochester New York, June 2001. This link will download a functioning version of the triple Venn diagram in Photoshop discussed this paper. The file is a Stuffit archive.