Re: poly: Why is brown common?

In a message dated 2/5/98 3:02:23 PM, carlf@alum.mit.edu wrote:

>The maxwellian hypothesis: There is some physical effect that frequently
produces
>a red-heavy reflectance spectrum that we identify as brown. I vaguely
remeber
>from my undergraduate classes in electrical engineering that is it common for
the
>amplitude response of circuits to decrease by 3 db for every octave of
increased
>frequency. Perhaps a 3 db/octave roll-off in the optical range looks brown.

In general, I believe that higher wavelenths are more absorbed in the visual
spectrum. I know that living tissue in general is pretty transparent in the
visual spectrum but quite opaque to even near-UV. The perception of "brown"
comes largely from a darker object particularly lacking in blue.

I think you're somewhat overstating the case for inorganics being brown.
Lots of sand and rocks come in yellow and gray.
Received on Sat Feb 7 00:17:01 1998