HDTV newbie

OK, I'm going to break down and buy an HDTV. But I have all sorts of
questions. I'm not a TV whiz, so these will be foolish but I'd like to
avoid making a big mistake.

Questions:

1. 1080p and 1080i.

1080i is an interlaced format which means that a portion of the picture
is rendered in one pass and a second portion is in another. I think I
understand how that would work with a CRT style tube, but how does it
work on an LCD or plasma where the number of pixels is fixed? I've
read some things that say that a 1080i signal is 'reconstructed' into a
full 1080 image and the rendered on a 1080p screen in a single 'pass'.
Does that mean that a 1080i source (satellite?) renders much better on
a 1080p TV than on a 720p one? If I have any of that even close to
being right (I'm guessing I don't), how does a 1080i LCD screen work?
How can you show interlaced video on a TV that has a fixed pixel count?

2. 1080p appearance

I've read some people saying that a 720p and 1080p picture don't look
too much different. For the life of me I don't get this one. Wouldn't
a full 1080p source (Blu-Ray) look way better than a 720p one based on
the extra resolution? I can understand how it wouldn't if you were far
away, but I would think that for normal TV watching that the difference
in extra detail would be noticeable, particularly if the screen was
large 50' or above...

3. 1080p sources

I gather that some 1080p HDTVs, particularly old ones, won't take a
1080p HDTV source. Yet they are still called 1080p. Is this because
they could accept input from another source (VGA) and render at full
1080 vertical pixels? If a 1080p TV lists HDMI input, does that mean
it will show the full 1080p BluRay HD-DVD resolution?

Sorry for the ignorance but I'm grateful for any help...

On 2007-01-11, Paul wrote:
OK, I'm going to break down and buy an HDTV. But I have all sorts of
questions. I'm not a TV whiz, so these will be foolish but I'd like to
avoid making a big mistake.

I'm six months ahead of you.

Questions:

1. 1080p and 1080i.

1080i is an interlaced format which means that a portion of the picture
is rendered in one pass and a second portion is in another. I think I
understand how that would work with a CRT style tube, but how does it
work on an LCD or plasma where the number of pixels is fixed? I've
read some things that say that a 1080i signal is 'reconstructed' into a
full 1080 image and the rendered on a 1080p screen in a single 'pass'.
Does that mean that a 1080i source (satellite?) renders much better on
a 1080p TV than on a 720p one? If I have any of that even close to
being right (I'm guessing I don't), how does a 1080i LCD screen work?
How can you show interlaced video on a TV that has a fixed pixel count?

No, you're mostly right. I'm told there are some Hitachi interlaced panels,
but the vast majority of fixed-pixel displays are progressive. Whatever signal
they accept, they deinterlace (if necessary) and scale (if necessary) to the
native resolution of the display.

1080i-1080p, when applied to film-based sources, ought to be perfect, but
life (and consumer electronics) is imperfect. See these articles for examples
of displays which do not deinterlace 1080i correctly:

http://hometheatermag.com/hookmeup/0506halfrez/
http://www.hometheatermag.com/hookmeup/1106hook/

Additionally, I hear many complaints about signal quality from
broadcast/cable/satelite. Which is better, 720p or 1080i may depend on the
signal source. I only watch DVDs.

2. 1080p appearance

I've read some people saying that a 720p and 1080p picture don't look
too much different. For the life of me I don't get this one. Wouldn't
a full 1080p source (Blu-Ray) look way better than a 720p one based on
the extra resolution? I can understand how it wouldn't if you were far
away, but I would think that for normal TV watching that the difference
in extra detail would be noticeable, particularly if the screen was
large 50' or above...

Well, it does depend on how close you sit. For a 1080p 37" display you have to
sit at about 4-5 feet to get full advantage of the resolution. I view mine
from about 7 feet, so I would probably be as happy with a 720/768 display. If
I were even farther, a 480 set would look just the same. And if you back off a
few hundred yards, everything looks like a single light bulb: 1 x 1
resolution.

Here is an article with resolution/distance charts:

http://www.carltonbale.com/blog/2006...p-does-matter/

3. 1080p sources

I gather that some 1080p HDTVs, particularly old ones, won't take a
1080p HDTV source. Yet they are still called 1080p. Is this because
they could accept input from another source (VGA) and render at full
1080 vertical pixels? If a 1080p TV lists HDMI input, does that mean
it will show the full 1080p BluRay HD-DVD resolution?

There has been much confusion, some of it mendacious. We must distinguish
between (1) the native resolution of the panel and (2) the signals it
accepts. (1) is the physical x-y count pixels on the display, eg: 1920 x
1080. People call this 1080p, but all fixed pixel devices (with the Hitachi
exceptions noted above) are "p", so that is redundant.

Panels accept a variety of signals over their various ports. 480i, 480p, 720p
and 1080i have been common for a while. 1080p has been rare until very
recently, and is limited to computers and DVD players. It probably won't be
broadcast. So we went through a period of panels that had 1080 vertical pixels
but which did not accept 1080p signals because there weren't any. They would
accept 1080i and others.

Plus: there are 720/768 panels which accept 1080i or 1080p signals and
downscale them to their native resolution.

Sorry for the ignorance but I'm grateful for any help...

You need to be reading various forums at http://www.avsforum.com/. There is a
lot of misinformation but you will spot the headcases pretty quickly.

A tip to save your eyes: go to the bottom of the page and set the style to
"AVS White".

-Bill
--
Sattre Press The King in Yellow
http://sattre-press.com/ by Robert W. Chambers
http://sattre-press.com/kiy.html

"Bill McClain" wrote:

A tip to save your eyes: go to the bottom of the page and set the style to
"AVS White".


Thanks for that tip - I had never noticed the setting. Much easier on the
eyes!

nospam wrote:
"Bill McClain" wrote:

A tip to save your eyes: go to the bottom of the page and set the style to
"AVS White".


Thanks for that tip - I had never noticed the setting. Much easier on the
eyes!



Useful information--thanks!