# Visible illumination in daylight



## davidclayton (Aug 8, 2008)

Are there some colours of light that are more visible in daylight than others?
For example, if I was outside during the day and I illuminated several LEDs of the same brightness, but each had a different colour, which one would be the most visible?

(I'm a newbie, so go easy :mecry


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## coolwaters (Aug 8, 2008)

dont think theres anything stronger then the giant ball of fire in the sky...

you can try blue light. our sun emits lots of red and green rays. or was it balanced?


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## TorchBoy (Aug 14, 2008)

davidclayton said:


> if I was outside during the day and I illuminated several LEDs of the same brightness, but each had a different colour, which one would be the most visible?


Um... if the LEDs aren't in a forest, and there _is_ someone there to see how bright they are, the one that was flashing.

:welcome:


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## Oznog (Aug 14, 2008)

Lumens is a scale adjusted for the human eye's response. Invisible infrared and ultraviolet have 0 lumens regardless of power for example. The human eye responds strongest to green, producing the greatest visibility per mw of light.

So for 50 lumes of red, green, or blue they should all be similarly "visible" in theory at least. However, you'll find green LEDs produce more lumens per device. That's largely because the optical power in mw is similar yet the human eye response factor scores green at more lumens per mw.


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## TorchBoy (Aug 15, 2008)

And yet the green LEDs are (when I last heard) still lagging behind the others in efficiency.


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## Ken_McE (Aug 15, 2008)

It's an interesting question. I don't think that any one color has a natural advantage, I think it would vary with the situation. A color that tended to match its background should be less noticable, one that contrasted more noticable.


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