[opendtv] Re: DVB considers SVC for 1080p and hierarchical
- From: Tom Barry <trbarry@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sat, 13 Dec 2008 08:09:12 -0500
Olivier -
Yes, that is more or less what I was asking. Again, it was a question
or conjecture, not a statement on my part.
My question was really about how much energy it takes to produce the
picture for a given (constant) screen size and viewing distance, not
counting decoding processing requirements? How much would the power
consumption change if you kept the screen size the same but added pixels
by increasing the pixel density? Much?
The part I'm not really clear about is how much power in the various
small display types is used for switching pixel states as opposed to
creating light, or back light? (as a percentage)
I suppose for a non-lit passive display viewed only by ambient light the
answer would be 100%, since no light is generated, but I really have no
idea what the percentage would be for typical portable displays these days.
- Tom
Olivier Houot wrote:
Regarding screen resolution/ power consumption, i think Tom takes the
abstract view that if you deliver the same power to the eye into the
same solid angle, then you should achieve the same result.
If you consider a screen of the same size with varying resolution,
indeed driving more pixels will require some more power, but won't that
be second order compared to what is used for back light ?
If light output is the dominant factor, then using for example OLED
technology with more pixel each with a proportional light output
reduction may not make such a big difference in the end.
But of course, processing high definition video in the phone will.
Note that this idea of identical power in the same solid angle would
allow for any screen size without changing the power, provided the
screen keeps the reflected power within the viewing angle. This is not
true for a standard projection screen, since here the purpose of a
large display is rather to spread information over a larger viewing
audience.
But it would be in the case of a virtual display created within
goggles. The constraint is that the definition has to be sufficient for
the highest possible screen size permitted by the device.
And by the way, this device is still a way to have perfectly mobile
HDTV. It is even possible to superimpose the picture on the normal
field of view without obstructing it, which would allow for some real
mobility while viewing (not that it would be highly recommended of course).
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