"Andrew Gabriel" andrew@a20 wrote in message
...
In article ,
"Dave Plowman (News)" writes:
In article ,
William Sommerwerck wrote:
And the same will apply to LED backlights. It's a big con that
LEDs are more efficient -- they only are where supplying narrow-
bandwidth light. As soon as you try and make them produce
continuous-spectrum light -- ie white -- the efficiency goes way
down. Of course, they may improve -- but then again, so may
fluorescent.

White LEDs are not continuous-spectrum. They contain a phosphor that
produces yellow light when stimulated by blue light.

Indeed. So not suitable for where you need a decent quality light. As for
an LCD backlight.

I don't see why an LCD backlight needs to be anything other than
red green and blue, and having just checked one, that's exactly
what it is -- actually very much narrower bands than a regular
fluorescent, and without any of the other fill-in colours you
get from a fluorescent lamp. After all, anything else from the
backlight would be wasted (or worse, might bleed through into
some colour cells and contaminate the primary additive colours).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Y
That depends on the assumptions you make in the production of the source and
the decoding to those narrow spectrum RGB displays. You may or may not end
up with the same distribution of secondary and intermediate colors. The
human eye perceives color over a spectrum approximated by the CIE standard
observer curves. Concentrating all of the energy at narrow bands can have
some very significant effects, not only in overall brightness, but in color
reproduction. While it is true that any color (within a given gamut) can be
made up of a combination of narrow band RGB display sources, getting the
right spectral power at a given color requires mapping from what the pickup
and encoding assume to what the display can produce. Unfortunately, there
are not many good options for measuring response at colors other than
primaries and secondaries and no good standards for evaluating performance
objectively at this time for intermediate colors, much less for those colors
over a range of luminance values.

Leonard