Ian Stirling wrote:

In sci.space.policy Christopher James Huff wrote:
snip
Well, we really are practically blind. Our eyes are trichromatic

Monochromatic-with-filters; or "quadrichromatic." But not "tri-."
11-cis retinal is the /only/ photosensor we've got.
The three oil filters (assorted among the "cones") reduce the
incident light level considerably, not the sensitivity.
Same happens putting color filters on a camera or litho
separations.

sensors, with limited resolution and only capable of giving very crude
estimates of color, lightness, and size. We can not see spectral

Looking at the spectral sensitivities, it's amazing there is
any vivid contrast between red and green at all.

Heh. Some few people have none whatsoever.
Monochromatic contrast is /all/ in the filters.

The two sensors are so similar that the difference in sensitivity
at any given wavelength between red and green is quite small.

Actually not; we are rather more sensitive to green by at least
e=hf.
Why subs and planes are set "cockpit red" at night.
--
-------(m+
~/)_|
The most essential gift for a good writer is
a built-in, shock-proof, **** detector. -- Hemingway
http://scrawlmark.org