[opendtv] Re: Optimizing the system

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Sun, 19 Dec 2004 10:45:54 -0500

At 7:20 PM -0500 12/17/04, Tom Barry wrote:
>Craig -
>Buy a 720p fixed pixel display at something significantly less than 100
>inches.  Sit for a few weeks at only 3 screen heights from it and look
>for the effect of highly textured objects moving across it like a swarm
>of bees.

Sorry Tom, but 720P is not designed to be viewed from 3 picture 
heights. 5 picture heights is closer to how these displays will be 
viewed in the real world. The swarming bees are more likely 
compression artifacts than a problem with the display, although I can 
understand that you might be seeing the individual pixels with plasma 
and LCD units (and possibly even DLP) at three picture heights. The 
size of the 720P display will also be a significant factor. If it is 
less than 50 inch diagonal then I doubt you would see the individual 
pixels , even at 3 picture heights. But as you increase the screen 
size beyond 60 inches I expect that you would see the pixels.

>Of course that is only display resolution, not delivery resolution.  But
>since that 720p display will last you for a few years, the next one will
>probably be a 1080p version since those will then dominate, and be
>cheaper MUCH cheaper.  At that time you will (in spite of the bees) have
>come to adjust your expectations and furniture such that you sit a bit
>closer.  You might then buy a large one in the 1080p range, though still
>not >100" since that is only for the front projector crowd.

I disagree. I think that 720P displays are going to dominate because 
they will be cheaper and will look just as good in the stores. Sorry, 
but when you are manufacturing "pixels," more pixels means higher 
cost. The LCD guys do have some incentive to move to 1080P so that 
they can make their rasters less visible, but this does not come for 
free, and I have not been hearing anyone talk about 100 inch LCD 
panels...yet. You only need 2 Mpixel resolution on these panels if 
they are going to be used for computing applications, like the Apple 
30" Cinema display.

>Of course I am still only talking about display resolution, not delivery
>resolution.  But wouldn't you be curious by that time what full 4:4:4
>1080p looked like?  And wish that since the space was available freely
>on the disc back in 1995 they had used it?

As Tom M indicated, if the source is progressive, you may not be able 
to tell the difference between 4:2:0 and 4:4;4 for normal TV and film 
images. Where it WILL make a big difference is when you are 
displaying Non--Nyquist limited imagery like web content.

>Or are we just still just arguing about the studies of how far people
>sit from their TV's?  I have already crept closer to mine in the 4-5
>years I've had HD.  HDTV's exert a strange attractor force on furniture.
>   It has been proven. ;-)

Actually just the opposite has been proven. In studies where people 
could freely choose the viewing distance for different size displays, 
they will only sit three picture heights from the screen when that 
screen is larger than 100 inch. For displays in the 50-100 inch range 
the preferred viewing distance is more like 5 picture heights. And as 
the displays get smaller, the viewing distance (in picture heights) 
increases all the way to about 8 picture heights for a 13 inch screen.

Everything I have seen suggests that viewing distance remains 
relatively constant, BECAUSE of furniture placement. So what is 
likely to happen is that the screens will get bigger, which has the 
same effect as decreasing the viewing distance as measured in picture 

That being said, there will always be exceptions.

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