1366x768?

[zacon]

Hi,

I'm thinking of buying a Panasonic TH-37PV500E plasma TV. This TV has a native resolution of 1024x768, while 720p is 1280x720. I understand that the reason this screen is limitet to this resolution is technology issues.

However,

The 50 inch version of this TV has a native resolution of 1366x768. A lot of other 50" plasmas have this resolution, too. Wouldn't it be better to have a true 720p screen with a native resolution of 1280x720, to avoid rescaling of 720p content? Why is the 1366x768 resolution so common?

Also, will the rescaling process from 720p to 1024x768 pixels result in noticeable loss of quality? Is it really that bad?

[PooperScooper]

With fewer pixels on the same size panel it means that the pixels will need to be bigger. This will cause you to see the "screen door effect" more easily -> you will see it at a greater distance from the panel than if it had more/smaller pixels. With a good scaler, more pixels are better in the same area. You don't read here Fujitsu P50 owners complaining that they wish their panels were 720p native. :) (Fujitsu P50s use Panasonic 50" plasma glass).

My guess for 1366x768 is that it produces the smallest pixel size that can be easily/economically produced. (and maintain square pixels).

larry

[FlipFlop]

I'll throw out a few wild theories:

768 is 3*256, so row addressing matches up with 3 x 8-bit addressing chips.

1024x768 is a common computer screen size, so existing panel layouts can be used for row addressing.

1080i minus 5% overscan is 1024 lines, and 768 = (3/4) * 1024, so scaling from 1080i is a "nice" factor.

1280*720 = 921,600 and 1366*768 = 1,049,088, so with the latter you get a "true" Mega-pixel display.

[zacon]

Hi,

I've done some searching around the forum as well as other places, and I found out the 37" version of the plasma I am thinking of actually have 720 lines. However, the 42" version has 768, but only 720 are used to view 720p content, because this will give a better picture quality than scaling to 768. This is probably the case for most TVs with 768 lines. I've heard complaints about tiny black fields on top and bottom of some screens.

Probably, the extra lines are there for better computer compatibility, as you talk about, which is an important factor today. You have a good theory with 768 matching 3 x 8 bit addressing, which probably makes the extra cost of having the extra 48 lines minimal.

I've heard that scaling from 1080 to 720 is nice because 720x1,5=1080. Ie. a factor of 3/2, which means three lines will become exactly two.

What you talk about is that four lines become three, which is also nice. I have no idea which of these are used, or if you can switch between them, but it could be easily checked by inputing a digital 1080i signal, and check for black borders on top and bottom. I personally think I would prefare black borders with no overscan rather than no black borders with 5% overscan.

I'm not sure if 1366x768 plasmas scale the rows when viewing 720p content either, somebody tried?

I'm sure the screen door effect is an important issue aswell.

[nameless33]

How about when using upscaling dvd players ?

The players I see all say 720p output in their specs, but few actually mention 1366x768 output. Wouldn't it defeat the purpose of outboard upscaling if you couldn't get the panel's native resolution ?

Then there's the issue of getting 1366x768 out of your typical set top box.

[zacon]

I've heard of DVD-players that can rescale a picture to 1366x768, but they aren't common.

Also, I've heard that people using 720p rescaled content from DVD-players on 1366x768 plasmas get black borders on all sides, but not with 1080i.

This points to that these peoples plasmas scale 1280x720->1280x720 and 1920x1080->????x1024->1366x768, with some overscan to make the scaling process smoother. (I have no idea what horizontal overscan is easiest)

It's probably different from plasma to plasma though, some might rescale 1280x720 to 1366x768 for all I know.

[PooperScooper]

All plasmas that I've seen or read about (including the 1366x768 plasma I own) have scalers to fill the entire 16x9 panel when given 16x9 input regardless of the incoming source resolutions (480p, 720p, 1080i). And most will take non 16x9 input and scale/stretch to fill the entire panel if you so desire. Stop with the analysis paralysis and go look at some! :)

larry