Digital BW, The Print

Austin,

Not quiet 'Bingo'; as Anthony said, I simplified things too much. We do have
two systems of vision, a luminance system which is the primitive animal
system - they can't see in color, and a color system peculiar to the higher
animals. Where I went wrong in my previous posting, in my attempt to keep
things short, was to say that the luminance system was due to the rods, and
the color system was due to the cones. Only partly true; cones are involved
in both systems, and primitive animals have cones, but only of one type
instead of our three, so no color vision. So it is true that our color
vision depends on cones rather than rods, but only because we have three
types of cones instead of the primitive animal's one type.

The two systems of vision are based in the nerves that connect the rods and
cones to the brain. Some take luminance info from both rods and cones and
discriminate edges, detail, movement, etc, while others take color info from
the three types of cones we have and overlay it on the luminance analysis.

In a very small nutshell, I think that is it, but the book I recommended is
very good, not just for its info on the biology of seeing, but for how it
explains the way that artists have used and do use our vision system to
their advantage, often without knowing anything of how it works.

Bob Frost.


----- Original Message ----- 
From: "Austin Franklin" <darkroom@...>
>
> Bingo, Bob.  Thanks for clarifying that point...it's what I meant by "both
> are active at any one time"...  We really only "use" about 1/4th
(spatially)
> the color information than we do grayscale information.
>
> > Color vision is believed to be a recent evolutionary add-on to the basic
> > animal B&W vision. Most animals don't possess the color add-on,
> > and do only
> > see in B&W.
>
> Was it a plug-in? ;-)