"William Sommerwerck" wrote in message
...
The LCD only filters light from the backlight. If you don't have a full
spectrum white in the first place the you can't expect decent colour.

Not so. All you have to do is hit the defined points in CIE diagram. The
Pioneer plasma sets hit them dead-on.



There is a little more to it than that, Bill. The points in the CIE diagram
are only part of what makes for a proper image. If you are referring to the
triangle of points on the colorimetry plot, you are only seeing the color of
the points, not the luminance. The resulting image is a matter of
saturation, hue, and luminance. You only see the first two with the CIE
chart that shows gamut.

The other aspect of getting the points on the colorimetry chart right is
that it tells you nothing about the colors in between and at different
levels. All it tells you is the color of the points you measure. How they
are mixed and create intermediate colors depends on the spectrum of each of
the primaries and the color decoding scheme in the display. The underlying
assumption in video is that we have a spectrum for each primary that is
similar to the CIE standard observer curves, which are approximations of how
we perceive color. When you deviate from those spectra you have to
compensate or you will be intermediate colors that have to much or too
little energy in a particular primary. There are no standards for how this
is done, because there are so many variations in backlighting and filters in
the displays. There are not even good metrics for getting to the bottom of
the problem yet.

The result is that the LED backlit displays can look very good, but
sometimes have a little strange color reproduction.

As for the black level and contrast ratios, they are only an improvement to
the degree that they can control backlighting locally. As the number of
controlled areas increase, the useful contrast ratio in an actual image may
begin to approach the on/off numbers that they advertise, but with less
zones of control, those numbers are simply meaningless to real video.

Leonard