On Wed, 16 Nov 2016 09:00:52 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/16/2016 12:58 AM, whit3rd wrote:
On Sunday, November 13, 2016 at 8:11:28 AM UTC-8, Leon wrote:

Fast forward and LED's lights now use, in many cases, yellow filters to
filter out the blue.

Actually, that yellow color is a phosphor; LED illumination starts with a blue
LED (sharp spectrum line) and generates other wavelengths with phosphors.
Fluorescents start with ultraviolet (from mercury in the gas of the tube) and
generate visible light with phosphors.



Excuse me for using the wrong terminology. But with out the yellow you
get blue, the point I was trying to make. ;!)

It's really the opposite of a filter. You're adding individual colors
(from phosphors) to get a perceived color, rather than starting with
all colors and filtering out the ones you don't want. If you look at
the spectrum through a filter, an incandescent with a filter will
produce a continuous spectrum. A fluorescent or LED will produce
bright lines with nothing between. That's why fluorescent and LED
tubes have problems with color "purity".