Brown is a mixture of the different primary colors. The primary colors
of light are red, green, and blue, which match up with the red, green,
and blue-sensitve cone cells in the retinas of our eyes. Since we only
have thee kinds of color-sensitive cells, you can make any color of
light (at least as it appears to us) with mixtures of just the three
primary colors.
I tried this with my computer monitor, running an application
which lets me dial in the strengths of the red, green, and blue
components, until I got something that looked rather brown to me. Here
are my mixture numbers:
Red: 164
Green: 84
Blue: 30
(255 is the maximum for each of these numbers in my program --
red=255, green=255, and blue=255 is the brightest white my monitor can
make). My favorite shade of brown is rather dark and is mostly red,
with a bit more green than blue light mixed in.
Technical note: the spectrum of light coming from a brown object
like a tree or some mud will contain all the frequencies of light in
the visible spectrum, with different strengths for each frequency. You
can examine this with a prism. But this broad spectrum of light is
indistinguishable to our eyes from light which contains only red,
green, and blue light in the appropriate mixture. If you were to look
at mixtures of perfecty red, green, and blue light through a prism, you
would get three sharp lines. The colors of mud and trees will give a
rainbow pattern which is brigher towards red end and dimmer towards the
blue end.
Tom
(published on 10/22/2007)
