The mysterious Blue Sensitive Eye Cones

There are far so many references to chromatic aberrations from
achromats and very few if none on prism diagonal (which has a
unique dispersing aberrations on primary colors and not secondary
spectrum) so I set out to find all information I can in the net. I came
across the following site which mentioned that the blue cones of our
eyes are few yet it has the same sensitivity as red and green courtesy
of some unknown blue boosting mechanism. If anyone has update
articles on the mysterious blue cones and detailed methods of achieving
the boosting effect. Lemme know. Thanks. I'd like to understand
the evolutionary process that leads to that selection. Birds have
4 color cones. Some species have more or specific cones including
seeing in the infrared and ultraviolet. Imagine in the not so distant
future when genetic engineering can render this same capability to a man.

http://hyperphysics.phy-astr.gsu.edu...colcon.html#c1

"In 1965 came experimental confirmation of a long expected result - there
are three types of color-sensitive cones in the retina of the human eye,
corresponding roughly to red, green, and blue sensitive detectors.
Painstaking experiments have yielded response curves for three different
kind of cones in the retina of the human eye. The "green" and "red" cones
are mostly packed into the fovea centralis. By population, about 64% of
the cones are red-sensitive, about 32% green sensitive, and about 2%
are blue sensitive. The "blue" cones have the highest sensitivity and are
mostly found outside the fovea. The shapes of the curves are obtained
by measurement of the absorption by the cones, but the relative heights
for the three types are set equal for lack of detailed data. There are
fewer blue cones, but the blue sensitivity is comparable to the others,
so there must be some boosting mechanism. In the final visual
perception, the three types seem to be comparable, but the detailed
process of achieving this is not known."

i was under the opinion that we used our 'rods' at night....



optidud wrote:
There are far so many references to chromatic aberrations from
achromats and very few if none on prism diagonal (which has a
unique dispersing aberrations on primary colors and not secondary
spectrum) so I set out to find all information I can in the net. I came
across the following site which mentioned that the blue cones of our
eyes are few yet it has the same sensitivity as red and green courtesy
of some unknown blue boosting mechanism. If anyone has update
articles on the mysterious blue cones and detailed methods of achieving
the boosting effect. Lemme know. Thanks. I'd like to understand
the evolutionary process that leads to that selection. Birds have
4 color cones. Some species have more or specific cones including
seeing in the infrared and ultraviolet. Imagine in the not so distant
future when genetic engineering can render this same capability to a man.

http://hyperphysics.phy-astr.gsu.edu...colcon.html#c1

"In 1965 came experimental confirmation of a long expected result - there
are three types of color-sensitive cones in the retina of the human eye,
corresponding roughly to red, green, and blue sensitive detectors.
Painstaking experiments have yielded response curves for three different
kind of cones in the retina of the human eye. The "green" and "red" cones
are mostly packed into the fovea centralis. By population, about 64% of
the cones are red-sensitive, about 32% green sensitive, and about 2%
are blue sensitive. The "blue" cones have the highest sensitivity and are
mostly found outside the fovea. The shapes of the curves are obtained
by measurement of the absorption by the cones, but the relative heights
for the three types are set equal for lack of detailed data. There are
fewer blue cones, but the blue sensitivity is comparable to the others,
so there must be some boosting mechanism. In the final visual
perception, the three types seem to be comparable, but the detailed
process of achieving this is not known."

On 15 Jul 2003 02:36:36 -0700, optidud wrote:

of some unknown blue boosting mechanism. If anyone has update
articles on the mysterious blue cones and detailed methods of achieving
the boosting effect. Lemme know. Thanks. I'd like to understand
[snip]

I know of no articles on the topic, but since blue light has the shorter
wavelength, it's going to register a hit more often than red or green to
begin with without any special "boosting" effect.




--
- Mike

Remove 'spambegone.net' and reverse to send e-mail.

"Mike Ruskai" wrote in message news:gunaalqrneguyvaxarg.hi2kk41.pminews@newstest 2.earthlink.net...
On 15 Jul 2003 02:36:36 -0700, optidud wrote:

of some unknown blue boosting mechanism. If anyone has update
articles on the mysterious blue cones and detailed methods of achieving
the boosting effect. Lemme know. Thanks. I'd like to understand
[snip]

I know of no articles on the topic, but since blue light has the shorter
wavelength, it's going to register a hit more often than red or green to
begin with without any special "boosting" effect.


Thanks for this explanation!

It's like x-ray with shorter wavelength destroying the chemical bond
of the DNA because it registers more hit.

optidud

On Tue, 15 Jul 2003 14:07:17 GMT, "Mike Ruskai"
wrote:

I know of no articles on the topic, but since blue light has the shorter
wavelength, it's going to register a hit more often than red or green to
begin with without any special "boosting" effect.

I don't think you can make this general statement. There are 5 different
chromophores in the human eye, all tuned to different wavelengths. The pigment
found in blue-sensitive cones, rhodonine-9, has only 56% the QE of the red
pigment and 70% of the QE of the green pigment. Since the pigment concentration
found in all the cones is the same, this means that the blue cones are
intrinsically less sensitive than the red or green cones (in addition to their
much lower density.)

It is perfectly possible to make a good RGB image using a sensor with a weak
blue response. It merely requires placing a higher weight on the blue signal
when combining the individual colors. Neural networks are very good at precisely
this kind of weighting. I see no reason that we shouldn't have good color vision
even though our RGB imaging system doesn't have intrinsically equal sensitivity
across each band.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

When viewing thru a flourite such as the FS-102 which
corrects for the color Green, Blue and Red, how come
the Violet blur can't be seen as if invisible? Only triplets
such as the AP, TMB, etc. corrects for Violet too but
not in the FS-102 or FC series yet the Violet fringe
that is supposed to be there can't be seen. However,
when we look at a person with a violet shirt, we can
see it, so what's the difference in the uncorrected
violet blur color of the doublets and the shirt. Both
should register violet. Even after consulting many sites
on vision and color. The explanation still eludes me.
Bottomline is, since my FC-60 only corrects for Green,
Blue and Red. I should violet fringe in any object with
contrasting outlines, yet it's not there. Is it because my
eyes can't detect it thru some unknown mechanism
and can I see the violet blur with filter (what filter?).

optidud

On 15 Jul 2003 19:18:38 -0700, (optidud) wrote:

When viewing thru a flourite such as the FS-102 which
corrects for the color Green, Blue and Red, how come
the Violet blur can't be seen as if invisible?

An apochromatic objective is corrected for three points. In a sense, that means
that nearly every color is uncorrected (except at those specific three
wavelengths.) Of course, this is not a real concern because the degree that the
other wavelengths are uncorrected is so small as to be indiscernible, or nearly
so. In particular, the eye is not terribly sensitive to short wavelengths,
especially in people over 40 or so. Also, the spatial resolution of the eye in
violet is very low. So while a few people may be able to detect some violet
fringing in an objective corrected in the blue, probably most cannot.


Only triplets
such as the AP, TMB, etc. corrects for Violet too but
not in the FS-102 or FC series yet the Violet fringe
that is supposed to be there can't be seen. However,
when we look at a person with a violet shirt, we can
see it, so what's the difference in the uncorrected
violet blur color of the doublets and the shirt.

What you call "violet" on a shirt is probably a radically different spectrum
than the spectrally pure violet you see dispersed by an optical system. The eye
is a very limited color sensor- there are thousands of different "colors" in the
sense that they contain different spectral content, but which look the same to
our eyes.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Chris L Peterson wrote in message . ..
What you call "violet" on a shirt is probably a radically different spectrum
than the spectrally pure violet you see dispersed by an optical system. The eye
is a very limited color sensor- there are thousands of different "colors" in the
sense that they contain different spectral content, but which look the same to
our eyes.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


Do you know of any device like a special flashlight or filter that can
create this spectrally pure violet color? I'd like to test how different
people can see it and who really can't... like shining the pure violet
light into a white paper and getting 40, 50, and 60 year olds to look
at it and tell if they can see anything. Just curious.

optidud

On 15 Jul 2003 19:18:38 -0700, (optidud) wrote:

When viewing thru a flourite such as the FS-102 which
corrects for the color Green, Blue and Red, how come
the Violet blur can't be seen as if invisible? Only triplets
such as the AP, TMB, etc. corrects for Violet too but
not in the FS-102 or FC series yet the Violet fringe
that is supposed to be there can't be seen. However,
when we look at a person with a violet shirt, we can
see it, so what's the difference in the uncorrected
violet blur color of the doublets and the shirt. Both
should register violet. Even after consulting many sites
on vision and color. The explanation still eludes me.

-snip-

the anwser is how we see colour, not optical theroy.

You see (poun intended), nto all peopel with so called
"normal" colour see colour the same. Teh textbook answer is people
with "normal " colour vbision see from 400nm (violet) to 700nm (deep
red). But evidence has shown some peopel see well into the near
ultra-violet. I think the US military is atually conducting tests to
see just how far, but published reports in trade journals suggest on
some individuals human sigt can go as deep or far as 320 nm into the
near ultra-violet.,

The other problem si when you are looking at a shirt, you may
or may not be seeing all that violet light. Some peopel cna also see
into the near IR according to some theories, so if the person is
wearing a cotton shirt - cotton reflects IR light - as iopposed to say
apolyester shirt - polyester passes IR light - the coloru cast of the
shirt may differ, even if the same dye is used on both fabrics.

I coudl go on and on, but yes, you are correct, most web site,
IMO, suck big tiem when ti comes to anexplaination fo human colour
vision. Even medical sites. They just simply don't get it.
joe



http://www.oneilphoto.on.ca

On Wed, 16 Jul 2003 12:07:05 GMT, (Joseph O'Neil) wrote:

You see (poun intended), nto all peopel with so called
"normal" colour see colour the same. Teh textbook answer is people
with "normal " colour vbision see from 400nm (violet) to 700nm (deep
red). But evidence has shown some peopel see well into the near
ultra-violet...

Interestingly, there is a UV sensitive chromophore in one population of cones
(response range 300nm-385nm, peak 342nm.) However, these cones normally are very
insensitive because UV is absorbed by structures in the eye before it can get to
the retina. The strongest absorber is the lens, which yellows with age, passing
less and less blue and UV. Eventually, cataracts develop and the lens is
removed. In recent years all replacement lenses include UV blockers, but plenty
of people are around who don't have these, and they have quite good UV
sensitivity. The same for children, with lenses that still pass shorter
wavelengths.


Some peopel cna also see
into the near IR according to some theories...

Although there is no specific IR receptor, the long-wavelength toe of the red
receptor extends quite far past the usually specified 655nm cutoff point, and
this chromophore has the highest QE of all. So any normal eye can see quite far
into the IR if the light is bright enough. This is easily observed with IR
remote controls. In a dark room, you can often see the emitter flashing dimly
red. What you are seeing is a fairly monochromatic light source operating
between 850-940nm.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com