Re: [Leica] Re:Color vision

[Aaron Sandler <aaron.sandler@duke.edu>]

While Larry makes many good points in his email about the tricolor approach 
to...well..color, I was surprised by the assertion that there are more than 
three types of cones in the human retina...I have never heard that before.

What I remember from my grad school coursework in 2000-2001 (confirmed in 
the review article I just skimmed--"Color Vision" in the Annual Review of 
Neuroscience, March 2003, 26:181-206) is that people do think there are 
three types of cones in the retina.  It's processing further along in the 
visual stream in the brain where it gets much more complicated.  Perhaps 
this is what Larry is thinking of?

Anyway, vision is clearly much more than the eyes, and much more than 
simply combining R-G-B.  In fact, the information from each of the 3 types 
of cones in the eye is kept separate all the way through the optic nerve 
into the brain.

The eyes are cool, but the real money is further along when many different 
specialized sets of neurons process edge detection, motion detection, 
pattern recognition, depth, visual memory, etc, etc, as well as color.

Now back to your regularly scheduled program...

- -Aaron

At 02:53 PM 2/2/2004, Larry Z  wrote:

>In a message dated 2/1/04 10:58:46 PM, Adam writes:
>
><<  The human eye uses more than three types of
> > color sensors - but then nature is not constrained by accountants or
>production
> > engineers.
>
>Really? What are there? I thought there were (in most people) three different
>sets of cones with different spectrum sensitivities and rods which are
>strictly
>luminance sensing.
>
>I'm not an expert though, and I don't play one on TV.
>
>What I have found fascinating is that we have built-in edge-detection and
>sharpening, which definitely supports our pattern recognition functions.
>  >>
>
>The last time I studied this area, I recall that there were five to seven
>different types of cones sensitive to various ranges of color in the human 
>eye.
>More may have been discovered recently. The idea that there are three 
>types of
>cones, each sensitive to a primary color stems from research done in the
>1880s. At that time Young and Helmholtz independently attributed color 
>vision to
>the operation of three types of cones in the eye (red, green, and violet).

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