Herbert Graf wrote:

> On Wed, 2009-11-18 at 18:44 -0700, YES NOPE9 wrote:
>> To be "white" is one required to include all wavelengths of light
>> from infrared to ultraviolet ?  I am not sure what that means. Or
>> does one just hit the high points of the cone cells ?
> 
> That depends on how you define "white". 
> 
> To the human eye, justing hitting the high points usually looks
> pretty white.

I had an interesting experience the other day (after this thread
started, or else I might not have stopped to notice it :)

I was in the attic, and sunlight shined at an angle through the window
at a standard cardboard-brown shipping box. The part that was
illuminated appeared white. When I blocked the light to the box, I saw
it as brown. But I couldn't make my eyes see it brown when the light hit
it, not clear brown, not even a hint of brown, just white... and the
light wasn't that high intensity. Strange.

Gerhard
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