How does SD resolution compare to HD

[admin_exported]

This may seem like a daft question but I'm going to risk derision and ask it anyway...

My ancient CRT telly has, I think, a resolution of 625 horizontal lines. What is the 'equivalent' digital pixel resolution of a standard analogue telly like this when it is playing a digital SD picture from my Sky+ box? I'm asking because on the face of it an HD ready TV with 720 horizontal lines (ie 720 x 1024 pixels) doesn't sound like much more (at least based on vertical resolution). Presumably it is as there wouldn't be all the fuss about HD television but I'd be interested to understand better why this is so.

Thanks,

Peter

 

[Andy TW]

The maximum viewable resolution of a PAL signal is 576 lines which is the most your CRT TV could have displayed.
The additional lines are used for teletext and other things which don't show in the SD picture.SD pictures will normally not look any better when displayed on an HD ready TV compared to a good SD CRT TV.However when fed from an HD source the picture on a good HD TV is noticably better.If you do not have an HD source then there is little benefit in terms of picture quality in changing to an HD TV (in my opinion).Wikipedia link explaining a bit more about TV resolution

 

[Anonymous]

We don't do derision. Or if we do, we oughtn't. You're right to assume that resolution measures don't necessarily apply to CRT sets, but if you were to look for a measure of equation between a CRT and a flat panel, it'd work like this. The CRT would expect to see 720 x 576 signalsÿ- the 576 lines being the active picture signal components of the 625-line PAL broadcast TV system, as another poster has commented. That's also the native resolution of Freeview, by the way.
An HD-Ready TV, meanwhile, must have a minimum 720-line resolution, as you point out, although this tends in most modern LCD sets to be of the 1366 x 768 variety, rather than 1024 x 720 or 1024 x 768: these figures are reserved mainly for the few remaining 37in and 42in plasma sets on the market. Then, of course, you've so-called HD-Ready 1080p screens, which provide 1920 x 1080 resolution, this being considered the optimum for pixel-to-pixel display of the 1080p content found on the likes of Blu-ray discs.
To go back to your point: you must remember that resolution is a factor of both horizontal and vertical pixel counts. A 720 x 576 screen has a pixel count of 414,720. A 1024 x 720 set takes that up to 737, 280: it might have 'only' 144 more horizontal lines of resolution, but it has 322,560 more individual points of light, or pixels, of screen information. Which is a lot. And obviously, an HD-Ready 1080p set has a wider margin of advantage, with 2,073,600 pixels to play with. The downside of all that resolution, though, is that it puts an awfully big load on the TV's scaler when you're asking it to display lower-resolution TV signals, such as Freeview.

 

[Anonymous]

And then again.... there is the theory that you should trust your own eyes, and not get to hung up about specifications. A good HD ready TV under 40" will show excellent SD, and will also handle HD very well.

TRUST YOUR EYES.

 

[Anonymous]

I can trust my eyes very well but even my local Panasonic shop doesn't seem able to show me all the TVs I'm considering to buy under all viewing conditions - clearly a full HD TV will look good with Blue Ray, but how will it perform with SD, or even broadcast HD? There are enough comments on this forum to suggest that the answer is perhaps not very well.

I am trying to choose one of the Panasonic 37" TVs so have to decide between HD ready plasma or Full HD LCD (ie TH-37PX80B or TX-37LZD85 or possibly the 800). I've just taken delivery of a Sky HD box and the kids have a large collection of regular DVDs they'll be watching - we don't own a Blue Ray player yet. So we'll be watching a combination of regular SD, some broadcast HD and regular DVDs (my player can upscale to 1080i). I will get a Blue Ray player at some point but will still be stuck with a lot of regular DVDs (I don't do any gaming). With this kind of viewing content (which so far as I can understand is all 720p) I'm not sure it makes sense to go for the full HD if everyone says the plasma has better basic picture quality than LCD (other things being equal) - also the Panny plasma is not much more than half the price of the top of the range LCD so one is £500 more than the other!.

Of course if I could compare the two TVs under all these viewing scenarios it would make life much easier but I haven't managed to find a store that can do that.

So my basic question is: if I am watching only SD and broadcast HD is there any benefit from a full HD television?

Thanks,

Peter

 

[professorhat]

[quote user="PeterHobson"]So my basic question is: if I am watching only SD and broadcast HD is there any benefit from a full HD television?[/quote]
Nope. Especially on a 37" TV IMO.

 

[Anonymous]

Quick and clear, that's the kind of answer I like! That's what I thought as well. Thanks very much professorhat.

Peter