Green as the Only Primary Color
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In Color Standards and Color Nomenclature, by Robert Ridgway (1912),
the author notes that "green [is], in fact, the only spectrum color that
cannot be made by mixture of the other colors" (p 19). Apparently, it was
believed that there were colors whose hues could not be reproduced by mixing
other colors (additive primaries for additive mixing and subtractive primaries
for subtractive mixing). Ridgway points out that this seems contrary to
his own experience, as he was able to produce pure hues of red, and blue
through additive mixing, but was unable to produce green in this way, so
presumably then red and blue could not be primaries by the then-accepted
definition. (This leads to the conclusion, not stated by him, that green
is the only primary.) It should be noted that this is not just a crackpot
book, as the author, curator of the United States National Museum's Division
of Birds, appears to have been quite a careful observer, and A Dictionary
of Color, mentioned below, describes this work and the author's preceeding
edition as having been standards of color-naming for scientists for decades.
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In A Dictionary of Color, by A. Maerz and M. Rea Paul, 2nd ed (1950),
the authors describe the case of Chineese Green, a dye that was brought
over in the 1700s or 1800s (XXXcan't remember now, have to check). Apparently
it was possible to produce any color of the spectrum with this dye merely
by carefully varying the dying conditions.
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If one takes the spectral response curve of the human eye and uses it as
a spectral intensity curve for a light source, that light will appear green,
as noted about the CIE (1931) green additive primary Y in G. A.
Agoston, Color Theory and Its Application in Art and Design, 2nd
ed, 1987.
Note for those who didn't get here from my home page: although this
is completely factual, it is nevertheless somewhat tongue-in-cheek and
not to be taken seriously.
Timothy Miller
Last
modified: Wed May 13 18:11:18 EDT 1998