"Dave Plowman (News)" wrote in message
...
In article ,
Arfa Daily wrote:
snip
There's no need for a display since it is theoretically possible to get
all visible colours from RGB. Mixing dyes is a different matter.
Theory, remembered from many years ago, suggests that isn't quite true.
I seem to recall my colour TV lecturer at college, spending a whole
session on 'the chromaticity diagram', and then explaining that there
were certain 'non-spectral' colours such as brown, which could not be
created by an additive mix of R,G and B, and any brown that was seen on
the screen was actually some kind of orange or red, which was
*perceived* as brown because of the surrounding colours, and other
visual cues. That might not be exactly it, as this was all learnt
nearly 40 years ago, but something close, I think.
Think that was more to do with the deficiencies of the then tube colour
cameras. Three or four tubes - usually Plumblicons. Which would show
Magenta as bright green, etc. And of course many CRT sets didn't use the
best phosphors - more concerned with how bright they'd go.
Well no, I don't think it was. Take a look at
http://www.yorku.ca/eye/nonspect.htm
which explains pretty much what I remember. The example of brown is quite a
good one, even with it shown in isolation - i.e. with no surrounding colours
and no visual cues. As an example of that, if it was a picture of a turd,
your brain might very reasonably *expect* it to be brown ...
As to whether LEDs as backlights do a good job, I'm sure that they must
be at least as good as CCFLs at colour rendering, otherwise, the
manufacturers wouldn't be making such a thing about it.
Heh heh - advertising? I play with LEDs quite a bit, and they are getting
better but still don't give as good a light quality as the best
fluorescents.
Flesh tones
look perfectly fine on digital cameras which use LED backlit displays.
Flesh tones contain a vast range of colour shades even on the one face -
unless it's Des O'Connor's makeup. Wasn't talking about a quick glance.
No, I wasn't either. I have two friends who both own top end digital SLRs,
one because he is a professional photographer, and the other because he is a
very keen hobbyist. I have looked at the viewfinder images closely on both
of these cameras, and the rendition of flesh tones in all the varieties is
excellent, and the professional of the two has commented to me how good he
thinks the viewfinder is at colour rendition under all light levels (input
that is, not viewing conditions).
Contrary to what you believe about the phosphors on CRTs, I don't believe
that there has been any significant change in their colour rendition
capabilities since the earliest delta gun tubes in the uk, which I worked
with from about 1970. Even back then, if you put in the time to ensure that
the decoder was correctly adjusted, and the CRT colour balance and tracking
was correctly set, they had the ability to render flesh tones superbly. In
fact this criterion was the main one we used to subjectively evaluate the
performance of a set, and was one of the main reasons for the broadcasters
using a little girl, whose skin was 'natural' and had no makeup, on test
card F. In contrast (no pun intended !) I think that the colour rendition of
most LCD TV sets - particularly in the case of flesh tones, is nothing less
than dreadful. So if LED backlighting improves on this - and the case of the
camera viewfinder images would tend to support this view - then that will be
good.
My whole issue with this, was that the LED 'angle' was being pushed by
wording that *suggested* it was the main display technology rather than
an LCD panel which it actually is, and which the great unwashed are now
familiar with. That seemed to me to be a deliberate attempt to mislead
people into believing that it was something new and revolutionary - as
SED technology will be if it ever gets on the market, or OLED if they
can get it big enough.
Well yes and I agree. They're pushing them on TV too. But I haven't
actually seen one. Perhaps they are as good as claimed. Cynical me doubts
it.
I don't have a problem with them claiming that this backlighting
technique is revolutionary in TV sets - it is - and even claiming a
reduction in power, if that's true, for a leg-up on the eco-bollox
ladder, but I really think that they should be making that distinction,
rather than trying to bamboozle prospective buyers with questionable
use of terminology which punters are likely to have heard of, but won't
actually understand.
On the power consumption issue, I still do not feel that this technology
is likely to consume anything like as much as the 100 or so watts that
CCFL backlighting does. The developments in the light output of
narrow-angle LEDs over the last couple of years is staggering. Some of
the 1 and 3 watt types could literally blind you. I believe that some
cars are now starting to use LED headlamps. It would be interesting to
see how they stack up against the 50 watt consumption of 'standard'
headlamp bulbs.
More to the point to compare with HID in cars?
Why particularly ? I was just trying to draw a comparison as to the relative
efficiencies of a 'standard' 50 watt halogen headlamp bulb, which we all
have a pretty fair idea of the brightness of, and the same thing in a LED
version, which is likely to be at least as bright, if not brighter,
otherwise there would be no point in the manufacturers trying to use them.
If the LED equivalent power consumption was say 10 watts, then we would know
that LED backlighting of LCDs was likely going to be more efficient than
CCFL backlighting, which we already know consumes around 100 watts to light
a 32" screen. If on the other hand the LED equivalent power was 50 or 75
watts, then we would know that it was going to be no better, and possibly
worse.
Thing is for domestic light my preference is halogen, quality wise.
Expensive fluorescent tubes can match that well enough. CFLs not. Nor any
LED I've yet tried.
Agreed all four points
Arfa
--
*The severity of the itch is proportional to the reach *
Dave Plowman London SW
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