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'[EE] Safe viewing colors?'
2005\04\21@233020 by Jinx

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Tagged [EE]

> Anyone have a link or doc that indicates which colors of (LED) light
> are generally better for displays -- easier on the eyes, quicker to read,
> etc?  I'm trying to find some facts on this, rather than just "generally
> known" info

I Googled for  eye "spectral response"  and got a lot of hits. This one
has a response curve

http://www.centronic.co.uk/products_electro_products_eyeresponse.asp

Seems to indicate ~ 550nm, which is green, which is where previous
threads like this have concluded (eg night vision goggles / light
intensifiers
are green)

2005\04\22@003359 by PicDude

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Hey Jinx,

I've heard much conflicting information on what we're most responsive to --
both red and green have been popular.  But other than response, I'm willing
to bet that the least destructive color (to our eyes) will be different.  
Pilots use red light since it has less persistence, but that does not
necessarily imply that it's the safest for long-term viewing.

Interesting search terms your used, but oddly when I type those in now, I do
not get that specific hit that you got.  Hmmm.

Cheers,
-Neil.


On Thursday 21 April 2005 10:29 pm, Jinx scribbled:
{Quote hidden}

2005\04\22@012931 by Hopkins

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Have you seen this link? http://www.theledlight.com/technical3.html


_______________________________________
Roy
Tauranga
New Zealand
_______________________________________



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2005\04\22@030100 by Jinx

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> to bet that the least destructive color (to our eyes) will be different.  

Is there *any* colour that is destructive ?

I'd have thought that the colour the eye is most responsive to can
be used at a lower intensity. As I mentioned, night-vision goggles
are green and used extensively and for long periods (search and
rescue, military). You might look around for health studies in those
areas

2005\04\22@043522 by Alan B. Pearce

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>I'd have thought that the colour the eye is most responsive to can
>be used at a lower intensity. As I mentioned, night-vision goggles
>are green and used extensively and for long periods (search and
>rescue, military). You might look around for health studies in those
>areas

I always thought that glow green more because that is an available phosphor
for the image intensifiers that has a short persistence time. Most yellow
phosphors (which is the colour I always understood our eyes are most
sensitive to) have very long persistence times (witness the long afterglow
on old analogue scopes with yellow screens).

2005\04\22@050510 by Russell McMahon

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Human eye is most responsive to a yellowish-green colour. Doesn't mean
it's the most pleasant to view though. Some emergency appliances are
this colour.


       RM

2005\04\22@054825 by Jinx

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Neil, do you have any reason to believe that any particular colour
is actually harmful or detrimental ? (apart from strong UV/IR/atomic
blasts, magnesium flashes etc which are harmful for reasons other
than colour)

For example -

o aborigines or desert people who see a lot of yellows and blues
o forest people who see a lot of greens and browns
o butchers who see a lot of red ? (just kidding - specious)

2005\04\22@083347 by Mike Hord

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> Neil, do you have any reason to believe that any particular colour
> is actually harmful or detrimental ? (apart from strong UV/IR/atomic
> blasts, magnesium flashes etc which are harmful for reasons other
> than colour)

Logically, I'd expect colors of light which our eyes are less responsive
to would be "damaging" in the sense that if we need to spend a lot of
time extrapolating data in that color, they would cause eyestrain
which over time MAY be detrimental to our eye health.  I don't know
about that, however.  If nothing else, you'll cause your users a load of
trouble.

Again, let me make my plea:  PLEASE don't use a yellow/green LED
as a status indicator.  People like me can't see the difference!  Avoid
things like that.  If you can, use a combination like blue/red- I think
that by avoiding red/green, yellow/green, or blue/yellow as
combinations for status indication, you'll make the lives of 99.9% of
the color-blind public much better.

Mike H.

2005\04\22@090825 by Jinx

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> Again, let me make my plea:  PLEASE don't use a yellow/green
> LED as a status indicator.  People like me can't see the difference!
> Avoid things like that.  If you can, use a combination like blue/red

I hadn't thought of the inconvenience factor - only ever used the
common R/G. Now that you've suggested alternatives I may look
into it for future products (would look cooler than R/G too)

http://www.lsdiodes.com/multi-color/

The B/W & R/W reminded me of another example of people
exposed to a lot of one colour - white (Eskimos), although UV
reflection probably causes problems, as in those who look at
bodies of water a lot

Straying from the point

http://it.stlawu.edu/~jahncke/clj/polarbearpics/PolarBears.html

2005\04\22@121405 by Peter

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On Fri, 22 Apr 2005, Jinx wrote:

> Tagged [EE]
>
>> Anyone have a link or doc that indicates which colors of (LED) light
>> are generally better for displays -- easier on the eyes, quicker to read,
>> etc?  I'm trying to find some facts on this, rather than just "generally
>> known" info
>
> I Googled for  eye "spectral response"  and got a lot of hits. This one
> has a response curve
>
> http://www.centronic.co.uk/products_electro_products_eyeresponse.asp
>
> Seems to indicate ~ 550nm, which is green, which is where previous
> threads like this have concluded (eg night vision goggles / light
> intensifiers
> are green)

Except anything but red ruins night vision and low intensity dark blue
seems to be the best for 'nightlight' type of appliactions.

Peter

2005\04\22@124706 by olin_piclist

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Peter wrote:
> low intensity dark blue

Phew!  I wouldn't have to come up with high intensity dark blue.

*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\04\22@130706 by Peter

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On Sat, 23 Apr 2005, Jinx wrote:

> I hadn't thought of the inconvenience factor - only ever used the
> common R/G. Now that you've suggested alternatives I may look
> into it for future products (would look cooler than R/G too)

Found on a forum suggested by you (in another context <g>)

http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Number=203850&page=0&view=collapsed&sb=5&o=all&fpart=1

Peter

2005\04\22@163911 by Russell McMahon

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> I hadn't thought of the inconvenience factor - only ever used the
> common R/G. Now that you've suggested alternatives I may look
> into it for future products (would look cooler than R/G too)

Red-Green colour blindness is by far the most prevalent form amongst
men - about 10%.
Far lower in women.

Interesting visual RG color-blindness test

       http://www.toledo-bend.com/colorblind/Ishihara.html



           RM

2005\04\22@172433 by Dave King

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Are you sure about the color blindness number? I thought it was
a bit lower than 10% for the male population, somewhere about 5%.

Good info though.


Dave

-> {Original Message removed}

2005\04\22@221349 by Russell McMahon

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> Are you sure about the color blindness number? I thought it was
> a bit lower than 10% for the male population, somewhere about 5%.

Stats vary by site. That came from a site that was dealing in
statistics of various sort and gave both a population stat and a
current incidence stat SO the 10% figure should hopefully be
reasonably OK.

       RM

2005\04\23@145220 by Peter

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On Fri, 22 Apr 2005, Olin Lathrop wrote:

> Peter wrote:
>> low intensity dark blue
>
> Phew!  I wouldn't have to come up with high intensity dark blue.

? Anyway 'night illumination' in places like hospitals and railroad
sleeping cars is dark blue. Apparently it does not disturb sleep or
something like that. It works for me at least. I think that it has to do
with the red tint imparted to light by closed eyelids. The blue does not
go through those 'filters' so the room appears to be darker than it
really is when lit blue and seen through closed eyelids. But I may be
wrong.

Peter

2005\04\23@153740 by Peter

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On Fri, 22 Apr 2005, Olin Lathrop wrote:

> Peter wrote:
>> low intensity dark blue
>
> Phew!  I wouldn't have to come up with high intensity dark blue.

Hmm, dark blue refers to quite far into the edge of UV, i.e. 450nm-ish
and lower. Now I understand the joke in your posting.

Peter

2005\04\24@014449 by Tony Smith

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> > Peter wrote:
> >> low intensity dark blue
> >
> > Phew!  I wouldn't have to come up with high intensity dark blue.
>
> ? Anyway 'night illumination' in places like hospitals and railroad
> sleeping cars is dark blue. Apparently it does not disturb sleep or
> something like that. It works for me at least. I think that it has to do
> with the red tint imparted to light by closed eyelids. The blue does not
> go through those 'filters' so the room appears to be darker than it
> really is when lit blue and seen through closed eyelids. But I may be
> wrong.

The movie industy has been putting blue filters on cameras to simulate night
for some time.  Funny how there always seems to be a full moon in all those
old movies...

Another reason for blue lights found in other areas (toilets, garages etc)
is that it makes it hard to find veins in your arms.  This makes injecting
heroin (or your preferred illegal narcotic) a bit difficult.  However, you
can use a marker (the one you use for breaking the copy protection on your
CDs) to mark out the veins beforehand.  High tech solution, meet age-old
cunning.

Tony

2005\04\24@042202 by Nigel Duckworth

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-------Original Message-------
From: Tony Smith

<snip>  High tech solution, meet age-old cunning.

TOO MUCH information!

I'm sure most of the people you were describing
have worked out this dodge for themselves but
why risk enlightening the odd one that hasn't
by broadcasting it?

Nigel Duckworth  

2005\04\24@093545 by olin_piclist

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Peter wrote:
>>> low intensity dark blue
>>
>> Phew!  I wouldn't have to come up with high intensity dark blue.
>
> ?

The point was that specifying "low intensity" together with "dark" doesn't
make much sense, since it gives the the impression that you could have a
high intensity dark light or a low intensity light one.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\04\24@094518 by olin_piclist

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Peter wrote:
> Hmm, dark blue refers to quite far into the edge of UV, i.e. 450nm-ish
> and lower. Now I understand the joke in your posting.

I've always understood "dark" or "light" to refer to intensity.  The "blue"
part refers to the hue.  Ordinary English is a bit ambiguous about
describing color saturation.  "Washed out" or "grayish" definitely refer to
low saturation, but there doesn't seem to be a universal term for high
saturation.  If the color happens to be red, then you can say "fire engine
red".  "Brilliant" can mean high saturation, but also high intensity
depending on context.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\04\24@105641 by Dave Lag

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Deep?

Olin Lathrop wrote:

> I've always understood "dark" or "light" to refer to intensity.  The "blue"
> part refers to the hue.  Ordinary English is a bit ambiguous about
> describing color saturation.  "Washed out" or "grayish" definitely refer to
> low saturation, but there doesn't seem to be a universal term for high
> saturation.  If the color happens to be red, then you can say "fire engine
> red".  "Brilliant" can mean high saturation, but also high intensity
> depending on context.

2005\04\24@221537 by Russell McMahon

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Cutting and pasting but preserving context:

>>>> low intensity dark blue

>>> Phew!  I wouldn't have to come up with high intensity dark blue.

>> Hmm, dark blue refers to quite far into the edge of UV, i.e.
>> 450nm-ish and lower. Now I understand the joke in your posting.

> I've always understood "dark" or "light" to refer to intensity.  The
> "blue" part refers to the hue.

Your understanding is understood.
As a joke the comment is somewhat obscure and therefore somewhat
excellent :-).

But, using the term "dark" and "light" to differentiate colours of
differing but
similar wavelength or mix of wavelengths is also extremely common and
time honoured.

Googling:

"dark blue" "light blue"            - 694,000

eg

"... Dark blue is associated with Oxford University and light blue
with Cambridge University."
____________

"dark green" "light green"        - 282,000
_________

You'll find in the vast majority of references that degree of
saturation / brightness is not the point of differentiation.

FWIW Many colours can not be produced from a single wavelength but are
a mix of pure wavelengths which our eye-brain systems assign a
"colour". The relative brightness of the 2 or more combined pure
wavelengths are varied to form various "colours", but for a fixed
ratio of intensities the "darkness" or "lightness" of the
resultant colour is not dependant on the combined absolute intensity.

See eg      http://others.servebeer.com/temp/ColourChart.jpg

   CIE Chromaticity diagram circa 1931!
   (Taken from Luxeon LED "all in one" app note.)

Note that using any 3 Luxeon LEDS does not allow a good rendition of
the whole of the colour space. The triangle formed on the CIE diagram
using RGB LEDs leaves out much of greeny-blue area. Using any 3 other
single wavelength colours also leaves out substantial area. By adding
CYAN to the usual RGB mix you get an irregular quadrillateral which
includes much more of the CIE colour space & so (obviously) greatly
increases available colour range. Using as "dark" a blue as possible
improves the range of possible colours produced. If only 3 LEDs are to
be used to produce as wide as possible a range of colours then a 518
nanometer emitter plus as "dark" a red and as "dark" a blue as
possible would be ideal. This is not available from Luxeon - the
nearest are cyan at 505 nm and green at 530 nm. The perceived colour
difference between these is large.



       RM


.



--------------------------------------------------------------------------------




2005\04\25@073441 by Gerhard Fiedler

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Olin Lathrop wrote:

> I've always understood "dark" or "light" to refer to intensity.  The "blue"
> part refers to the hue.  Ordinary English is a bit ambiguous about
> describing color saturation.  "Washed out" or "grayish" definitely refer to
> low saturation, but there doesn't seem to be a universal term for high
> saturation.  If the color happens to be red, then you can say "fire engine
> red".  "Brilliant" can mean high saturation, but also high intensity
> depending on context.

Wouldn't "clean" usually imply high saturation when applied to color?

Gerhard

2005\04\25@081834 by olin_piclist

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Gerhard Fiedler wrote:
> Wouldn't "clean" usually imply high saturation when applied to color?

Hmm, I suppose it could in some contexts.  I was looking thru some
references and found "vivid" and "bold" as the best words so far for
describing highly saturated colors.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

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