LED color?

I've always preferred a near-white LED, in part because some greenish colors are pretty unattractive. But I was playing with a white LED light and a hotwire last night and was -- again -- struck by what seemed like better target color perception with the hotwire. So I was wondering, would a yellowish or yellow-orange LED give better color recognition than a white LED? Is there a color that's known for optimum color perception?

Here are the notes that I have made on Luxeon bin colors. Hopefully this will both save the experts some time in answering this common question and get me some more updates for my notes:



Info on LED bin codes is available at: http://home.comcast.net/~theledguy/bin_codes/

tint codes:
V1: yellow or orangish, most like incandescent (ideal for outdoors)
X1: very slight yellow-green tint

V0: even warmer white??
W0: warm white, sometimes has a faint yellow tint (most popular bin, the ideal 'wallhunter')
X0: cool white (purest white, least variation of within the bin, may appear purplish when compared to an X1)

Y0: pale blue tint
YA: purple-blue??
WA: purplish??

[0 = on the Planckian BBL line, 1 = above the line, A = below the line]
[Y = cool(blue or purple), X = middle, W = middle, V = warm(yellow or orange)]


Q: So what is the difference between X0 and W0? Any visual difference? Is X0 whiter?
A (by PhotonFanatic): Yes, there can be a visible difference. The W0 will tend to be the warmer looking of the two, often with a faint yellow tint to it. Mind you, this is not objectionable to most people. In fact, the W0 bin is perhaps the most popular bin. However, the X0 is most likely to be the purest white tint available from Lumileds. Also, there is less variation within that bin compared to, say, the W0 or Y0 bins. The Y0 bin usually has a pale blue tint to it, and is also fairly popular with those liking a HID-type of tint.

Q: What does the X1 tint look like and how much variation is there in perceived tint within the bin? I'm still fairly new to the Luexon tints but I've learned enough from reading to know that I should pay attention to those middle letters too.
A (by andrewwynn): The X1 is a bit more 'natural' than the pure-white of W0.. it has a very slight yellow-green tint, but only can really see with a direct comparison to other lights... the X0 or WA are very 'purply' in comparison. It's not green enough to really take advantage of the 'outdoorsy' color like the V1 tint, so it's a bit of a compromise between the ideal outdoor (V1) and the ideal 'wallhunter' W0.

"I've always preferred a near-white LED, in part because some greenish colors are pretty unattractive. But I was playing with a white LED light and a hotwire last night and was -- again -- struck by what seemed like better target color perception with the hotwire. So I was wondering, would a yellowish or yellow-orange LED give better color recognition than a white LED? Is there a color that's known for optimum color perception?"


Hi there,

Yes, but it's usually referred to as 'color rendering', which simply means
if you shine the light on all colors they show up to the human eye in
a certain way, and the best color for best color rendering is Daylight,
with color temperature 6500 deg K.

A really good example of where this becomes important is when cooking
red meat (and possibly other types of meat too). If the meat appears
a 'red' color in the inside (after cutting with a knife) then it's not
'completely' cooked. If a tinted light is used it might not be possible to
tell the difference between 'rare', 'medium', or 'well done'. With a good
white color light you can see the red even when it's almost well done.
I've noticed that when cooking chicken it's almost the same. If there
is still a little blood coming out of the meat it's hard to see with lights
that are tinted yellow/orange and even green, but with white light
(daylight) you can see it.

Another example is when comparing tooth color (dental apps for making
false teeth). Some tooth color tints wont be as apparent if the light is
already tinted.


Take care,
Al

Some basics. First of all, when you see a colored object, what your eyes are actually receiving is the reflection of that color from the light source in use. Or in other words, that colored object absorbs all the other colors of light in that light source, except what you see.

Once you grasp that, it becomes pretty obvious that in order to see a colored object correctly, that color light must be present in the source to begin with. If the light isn't there, there's nothing to reflect, and the object will appear a neutral tone or it may disappear altogether depending on the background.

Daylight and incandescent light both contain a pretty similar spectrum of colors, and therefore they both render colors similarly. Daylight is normally considered the "standard" for color rendering.

Daylight and incandescent can also be correlated to an equivalent Color Temperature per the physics of a Black Body radiator. Noon-time sunlight on a clear day is usually said to be around 6500K. BUT! This is where it gets interesting. Any other light source (for example LED, fluorescent) that is also tweaked to produce 6500K correlated color temperature will NOT have the same color rendering ability!

Why not? Because the relative amounts of the different colors of light in the fluorescent, or LED, are markedly different from the spectrum of daylight/incandescent. Remember, the light has to be present in the spectrum of the light source in order for you to see the colored object correctly. If your source is heavy on blue and yellow (using the white LED for example) it'll do fine on blue objects and yellow objects but not so great on red objects.

One more time, in summary: there is no direct connection between correlated color temperature (CCT) and color rendering index (CRI).

Hope this helps.

Best regards,
Steve Offiler
VP of Engineering
Central Tools, Inc.

Hello again,


I find the fluorescent bulbs rated for daylight (D suffix) render colors pretty well.
To contrast, the ones with the WW and CW suffix arent worth a crap (he he)
because they throw an orange-ish glow on the object being viewed.

You know what else just so happens to be so interesting? There seems to be
no 'exact' system for determining how a given light source will render your
chosen particular color (good, medium, bad). For the example i gave in
the earlier post this was 'red' for viewing cooked meat colors, but also
'brown' and 'white' (cooked beef or cooked chicken). It would be nice to be
able to open a catalog of bulbs (fluor) or LED's (white) and see which LEDs
or bulbs would be best for viewing red, brown, and white. If you could find
a bulb that worked good for those colors then you could buy it for your kitchen
rather than one that didnt render one of those three colors very well.
I guess in this case, at least for now, we have to go with experience and what
has worked for us in the past...ie Daylight 'D' fluor tubes for the kitchen, and
maybe the 'CW' tubes for whatever else (although i dont know what except to
cast a warmer feeling color on everything).


Take care,
Al

Hello again,

I did an experiment yesterday with some chicken.
Cooking a leg in the microwave, then taking it out at some point when
it might be done...then...
1. First looking at the inside of the meat while it's lit with a CW fluor tube.
2. Then looking at the inside of the meat lit with a white LED with fairly white output.

When first looking at the meat with the CW tube, it looked like it wasnt cooked
enough yet, and had to go back in for a few more minutes.
When looking at the meat with the LED light, it was clear that it was cooked.

So, one light made it look cooked and the other made it look not cooked.
How do we know which one is right?

Tasting the meat it did taste like it was cooked completely, so i tend to believe
the LED light over the CW tube. Also, it looked cooked with another LED light
which i believe puts out a very pure white light (from experience colors seem to
show up good with this light and it doesnt seem to have any tint when it's shone
on colors believed to be almost pure white).


Take care,
Al

Flourescents annoy the heck out of me... likely caused by the 50Hz strobe effect.

As was pointed out, most LEDs are considered WHITE unless they are compared to each other. My WX1S LuxeonV Mag mod is considered white unless compared against my Peak Mediterranean were the slight greenish/yellow tint is mildly noticable. Since the LuxV is used outdoors, I prefer the tint so no problems there.

Comparing my three main lights, they all have slight tint variations that are not noticed unless directly compared. The WX1S Luxeon Mag is every slightly yellow/greenish, the Mediterranean is white and my Fire~Fly III is slightly violet.

Luxeon tints were much easier in 2002! It was obvious when in use but now, the only way I notice is the CPF white wall direct comparison. It is a good thing to see that it takes so much work to notice tints these days.

All that cookin' talk has made me hungry:naughty:.

That aside, someone wrote that the -V1- bin LEDs are "yellow or orangish, most like incandescent (ideal for outdoors)" I looked at Photon Fanatic's (aren't we all!) site and he didn't list any -V1- LEDs. Are there other opinions about this bin? Can they be bought, say a Lux3 TV1-?

Hi there Leef,

Sorry i cant answer your question but im sure others will read your post and
might have some ideas, but i couldnt help but laugh at your signature lines

That's the best definition for the 'precision instruments' we use i've seen so far!

Hee hee, and take care,
Al

Why don't we see many V0 or V1 tint LED's?

The X0 and W0 seem to be the most popular tints, but I have been watching the threads with LED's for sale and it seems that there are far more LED's with the Y0, YA, WA, and X1 tints available than there are for the V0 or V1 tint.

Are the warm V-tint LED's just rarer than the other tints or does somebody else buy up most of the warm tint LED's?