[opendtv] Re: 1080p questions
- From: "Stessen, Jeroen" <jeroen.stessen@xxxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 9 Dec 2009 09:34:42 +0100
Hi,
John Shutt:
Ø I'm sorry, Jeroen, but I just cannot agree with one of your points:
>> - make shutter glasses that are not based on polarization, which
>> would be a very
>> good thing for displays that do not emit already polarized light (plasma,
>> DLP)
Ø This is not true. LCD (polarized) shutter glasses are already a very good
thing to
Ø use with displays that do not emit polarized light, because it avoids the
pitfalls
Ø I've outlined with existing LCD displays.
That's not what I meant. I understand the positive point that you refer to, but
the
disadvantage remains that the first polarizer of the LCD shutter glasses must
take
away 50% of the light if the light was not already polarized in the same
direction !
Add to that the fact that each shutter opens for only 50% of the time (or
less), and
you have reduced the brightness of your plasma or DLP display to 25% or less.
The 50% factor is unavoidable in any multiplexed system (you would need two
displays, one for each eye, to avoid that), but any further loss is just a
waste.
Ø As you yourself noted, when wearing LCD shutter glasses, you are subjecting
the
Ø wearer to, as you put it, "[a]lso, your entire world will be viewed through
shutters,
Ø this may cause issues with CCFL lamps, street lamps, fluorescent
time-multiplexed
Ø displays on video players, other displays in the same room, etc." Therefore
I think
Ø we are in agreement that LCD shutter glasses would work very well with
plasma or DLP displays.
Yes, they work very well, but you could try to find a better alternative that
leaves
you with twice as much light. Something that does not depend on polarization.
Okay, admittedly, the rest of the room is also dimmed to 25% or less by the LCD
shutters, so your eyes would adapt, and you would not notice it as much.
This assumes that the glasses provide good shielding all around your eyes, but
with
LCD shutter glasses being entirely flat, this is not quite the case. It all
works well
enough in a dark (digital) cinema, but it may not work as well in a typical
living room
situation. The demos I've heard of had much less than 25% effective light
output.
Note also that your eyes become significantly slower at low brightness, so you
won't mind the 24 Hz judder anymore, but any fast action will be lost on you.
Ø Shutter glasses that are not based on polarization would be a very good thing
Ø for LCD displays! What technology that would be based upon is another
matter.
Good yes, necessary no. What 3D-ready LCD displays that there will exist will
come
with shutter glasses that work for the direction of the polarization of that
LCD display.
As long as you keep your head straight within approx. +/- 45 degrees it will be
just fine.
You would not want to tilt your head any further than that, because the
stereoscopic
image presumes two eyes on a horizontal line anyway. It's not holographic...
Auto-stereoscopic displays (i.e. no glasses) do not suffer from brightness
loss, but
then the spatial resolution must be divided by two or more viewing angles, so
you
will lose sharpness. I guess the only winner here is the near-eye display,
where two
miniature displays are built into the goggles. It may be not so, eh, practical ?
Groeten,
-- Jeroen
Jeroen H. Stessen
Specialist Picture Quality
Philips Consumer Lifestyle
Advanced Technology (Eindhoven)
High Tech Campus 37 - room 8.042
5656 AE Eindhoven - Nederland
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