Please explain

(BUFDRVR) wrote in message ...
Green + Red = Blue???
Mind boggles.

hmm, doesn't it? I have an idiglo Timex that has a blue light, I was told by
the NVG instructor in my squadron that it would work well enough, but would
have been better if it were green. He then gave me that exact line I gave you
above, anything with shades of red in it will tend to wash out NVGs. Anyone out
there have a clue better than mine? Any color spectrum experts?

I believe what he was referring to is the fact that red, green, and
blue are *the* primary colors. As blue is one of those primary colors,
it is not a product of the other two. Red plus green actually yields
yellow.

Brooks



BUFDRVR

"Stay on the bomb run boys, I'm gonna get those bomb doors open if it harelips
everyone on Bear Creek"

BUFDRVR wrote:

Green + Red = Blue???
Mind boggles.


hmm, doesn't it? I have an idiglo Timex that has a blue light, I was told by
the NVG instructor in my squadron that it would work well enough, but would
have been better if it were green. He then gave me that exact line I gave you
above, anything with shades of red in it will tend to wash out NVGs. Anyone out
there have a clue better than mine? Any color spectrum experts?


BUFDRVR

"Stay on the bomb run boys, I'm gonna get those bomb doors open if it harelips
everyone on Bear Creek"


The green plus red is blue boggles my mind.

Still,

I wouldn't call myself a colour spectrum expert, but I'll give it a try:
The NVGs are most sensitive to light at the low frequency/ long
wavelength end of the visual spectrum, i.e. the red end of the spectrum
(and unlike the human eye even is sensitive to somewhat lower
frequencies in the IR range).
Green is associated with higher frequencies/smaller wavelengths than
red. A red light of a certain intensity produces a far stronger response
in the NVG than a green light of similar intensity would, since green
lies further away from the wavelength range to which the NVGs are most
susceptible. Pretty straightforward.
As for the blue, this is associated with even higher frequencies/smaller
wavelengths than the green, so it should be even less visible, which
gives no explanation whatsoever for why green would work better than
blue, unless with blue the worry would be that you wouldn't bee able to
see that at all, while wearing your NVGs.

Regards,
Ralph Savelsberg

In article ,
(Kevin Brooks) wrote:



I believe what he was referring to is the fact that red, green, and
blue are *the* primary colors.
Er, isn't that red, green, and yellow?

KeithK wrote:

In article ,
(Kevin Brooks) wrote:



I believe what he was referring to is the fact that red, green, and
blue are *the* primary colors.

Er, isn't that red, green, and yellow?

There is no such thing as "the primary" colours.


Colour is a very subjective thing.

If you're dealing with paint it would be red, blue and yellow (or Cyan,
Magenta and Yellow)
If dealing with light the most commonly used one would be red, blue and
green (RGB)

The human eye contains two different types of light receptive cells:
so-called cones and rods. Cones are used in light with relatively high
intensities and are responsible for colour vision. Visible light is only
a very small part of the electromagnetic spectrum, between 380 and 700
nm. Light of a certain spectral wavelength appears to us as a colour,
but light from a single wavelength is not the only way to create the
sensation of that particular colour. Different spectral distributions
can produce an indistinguishable colour sensation. The commonly accepted
theory for how colour vision works is that the cones in the human eye
contain three different pigments, with three different absorption
spectra: a pigment most sensitive to light around 450 nm (blue), one
most sensitive to light with a wavelength of 550 nm (green/yellow) and
one most sensitive near 570 nm (yellow/orange). That is why combinations
of three primaries, for instance red, green and blue can be used to
create pretty much every colour sensation.

A fine explanation of colour vision can be found in `The Feynman
Lectures on Physics', by Richard Feynman, of which every self-respecting
library should have at least one copy.

Regards,
Ralph Savelsberg

In article ,
(KeithK) writes:
In article ,
(Kevin Brooks) wrote:



I believe what he was referring to is the fact that red, green, and
blue are *the* primary colors.
Er, isn't that red, green, and yellow?

Well, that would be inks, instead of light. And it would be Red,
Blue, and Yellow. (Actually, it would be Magenta, Cyan, and Yellow,
as in the CMYK notation used by printers to define colors.

Light is Red, Green, Blue, as in an RGB computer monitor.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

Ralph Savelsberg wrote in message ...
KeithK wrote:

In article ,
(Kevin Brooks) wrote:



I believe what he was referring to is the fact that red, green, and
blue are *the* primary colors.

Er, isn't that red, green, and yellow?

There is no such thing as "the primary" colours.

Well, most generally consider RGB to be the primary colors of light,
and that is the subject under discussion here.



Colour is a very subjective thing.

If you're dealing with paint it would be red, blue and yellow (or Cyan,
Magenta and Yellow)

But we are not dealing with paint (for which the proper selection is
the latter, IIRC).

If dealing with light the most commonly used one would be red, blue and
green (RGB)

Exactly.

Brooks

snip

Clark wrote:
"James Hart" wrote in
news:born99$1hucui$2@ID- 76251.news.uni-berlin.de:

BUFDRVR wrote:
I'm thinkin that with NVS, the lights are blue? Not sure, but it
would make sense. I know before NVS came out the formation lights
were all green, but this would overdrive and blind NVG's.

Actually Green lighting is better than Blue lighting for NVGs.
Anything with shades of Red light (Green + Red = Blue) will wash out
the NVGs.

Green + Red = Blue???
Mind boggles.

No boggle, just an alternate color reality.
:-)

Makes for some purdy camo schemes I'd guess .

--
James...
http://www.jameshart.co.uk/

The green plus red is blue boggles my mind.

Still,

I wouldn't call myself a colour spectrum expert, but I'll give it a try:
The NVGs are most sensitive to light at the low frequency/ long
wavelength end of the visual spectrum, i.e. the red end of the spectrum
(and unlike the human eye even is sensitive to somewhat lower
frequencies in the IR range).
Green is associated with higher frequencies/smaller wavelengths than
red. A red light of a certain intensity produces a far stronger response
in the NVG than a green light of similar intensity would, since green
lies further away from the wavelength range to which the NVGs are most
susceptible. Pretty straightforward.
As for the blue, this is associated with even higher frequencies/smaller
wavelengths than the green, so it should be even less visible, which
gives no explanation whatsoever for why green would work better than
blue, unless with blue the worry would be that you wouldn't bee able to
see that at all, while wearing your NVGs.

Wow, this thread has gotten good, imagine that I'm actually learning here.
Unfortunately, I obviously misunderstood the NVG experts words, I thought he
said blue light was closer to the red spectrum than green, but if you're
correct (as well as another poster who posted the exact frequencies for each
color...impressive), I must have misunderstood. Anyway, he was correct, my blue
indiglo watch washed out my NVG's, if only slightly, while the green light of
similar intensity did not.


BUFDRVR

"Stay on the bomb run boys, I'm gonna get those bomb doors open if it harelips
everyone on Bear Creek"

(Kevin Brooks) wrote:

If you're dealing with paint it would be red, blue and yellow (or Cyan,
Magenta and Yellow)

RGB corresponds to the color detectors in the retina.

With paint, as in having it mixed at the hardware store, one uses a bunch of
colors, like 10 or 12 to form a polygon in the color space and give a much
larger pallet of colors. Just RGB or CMY gives a triangle and leaves out a lot
of the perceivable colors. See any chromaticity diagram (which is three
dimmensional and usually shown as two with shading for the third).

It is possible to "see" colors that do not exist in the electromagnetic
spectrum, like brown. Likewise, the orange from red+yellow is a product of the
brain and retina as opposed to an orange spectral line from a sodium lamp. They
look the same to us but a simple filter will show the difference.

So, what and NVG will react to can be auite different from what the eye alone
will react to.

Most of modern color/brain theory comes from work by Land who found ways to
"fool" the brain into seeing full color with just two colors in the projection.

Photographers talk about addititive and subtractive colors depending on whether
a process uses primary dyes or filtering gels.

But we are not dealing with paint (for which the proper selection is
the latter, IIRC). BRBR

-- Charlie Springer

The Feynmann is of course a very good reference.

In article ,
(KeithK) wrote:

In article ,
(Kevin Brooks) wrote:



I believe what he was referring to is the fact that red, green, and
blue are *the* primary colors.
Er, isn't that red, green, and yellow?

Red, green, and blue are the additive primary colors. You can get
anything from combining those. (See your color monitor.)

The subtractive primary colors are cyan, magenta, and yellow; the three
(with black to help improve contrast) get you all the colors that you'll
find in, say, National Geographic magazine.