HDTV resolutions

[CK1]

I am looking to buy a HDTV Ready Plasma TV most likely (the Pioneer PDP-436XDE or the PDP-506XDE are my dream choices) within the next 6-9 months or so, but I have a question that no-one seems able to answer.

Both of these screens and most other HDTV screens display 768 verticle pixels which is fine for 720p, one of the standard resolutions for HDTV, but I'm at a loss how these screens display 1080i or 1080p?

Surely a screen that needs to display 1080i/p will need this number of verticle pixels. If this is not the case then can anyone who knows the answer please share it with me.

Also, as a side point, if the screen has 768 verticle pixels and displays an image that is 720 pixels high will it lose out on 48 verticle pixels? In which case are there going to be very small black bars at the top or the bottom?

[Funkstar]

Simple, the image processor in the screen scales the image.

1080p plasma screens are in the £8,000 to £10,000 range at the moment i believe. There was even a post on Engadget a couple of months ago about someone releasing the smallest 1080p plasma at 42" all the others were in the 50" plus range.

[directhex]

the HD-Ready spec in the UK doesn't require that a screen has a 1080 vertical resolution - merely that it has a 720 vertical resolution and can decode 1080i signals if needed.

look at it this way - a 1280x720 lcd screen is 0.9M pixels, a 1920x1080 screen is more than twice that - making them prohibitavely expensive to manufacture (and therefore unlikely to be in many homes)

[MSIC]

A 1080i picture doesnt need 1080 lines, it only need 540 lines - it will then interlace them (1080i) by showing one frame then another frame, each of a completely different set of lines (so a 60Hz signal in america displays 30 frames per second, a 50Hz signal in the UK displays 25 fps).
I hate interlacing and was delighted when i heard about 720p - a proper resolution! It's actually a shame in my view that 1080i is an option - i want to get rid of interlacing for good.

[5lab]

misc you're wrong. it needs 1080 lines, but only displays each line every other frame, otherwise it'd look like the picture was spazzing up and down by 1 line every frame

[MSIC]

Really? So a 1080i picture on a 768 res screen is interlaced, scaled down and scaled up again? Jesus.... crappy picture quality.
Well in that case, er.....ok then.
Will investigate further in the morning. Tired. Need sleep...

[5lab]

its interlaced then scaled down to the native res.. thus it wont look any better than 720p on most hdtv sets (in fact, it may look worse)

[MSIC]

Yep, seems you are spot on - for a proper 1080i picture you would indeed need 1080 lines, it would just only be showing them odds then evens alternately.
So scaling is necessary etc.

[Chant] Down With Interlace, Down with Interlace [/Chant]

[Howard]

Even if you did have a 1080i compatible display, the interlacing on 1080i would not be nearly as irritating as with normal PAL definition of 625 line interlaced, simply because of the resolution, there will be less jaggies, etc

1080p will be nice though

[CK1]

Does my original point stand then? That in order to see 1080i/p in it's proper level of detail you need 1080 verticle lines? Presumably all signal processing will do is scale down 1080 lines to 768 and you will therefore lose detail.

In that case how does 1080i look on a screen with 768 lines compared to 720p?

[5lab]

Does my original point stand then? That in order to see 1080i/p in it's proper level of detail you need 1080 verticle lines? Presumably all signal processing will do is scale down 1080 lines to 768 and you will therefore lose detail.

In that case how does 1080i look on a screen with 768 lines compared to 720p?

pretty similar - except you may get interlacing artifacts on 1080i. they're both scaled to fit the screen, so neither has a 1:1 pixel mapping, however for films etc this isnt nearly as noticable as it is for text ( where it appears slightly 'soft').

in fact.. even on a 1080 screen, the interlaced picture would probably be converted to progressive to display better - thus more artifacts..

afaik, 1080p is not yet in the hdtv standards.

[dmuz]

TVs where so much easier to understand 30 years ago. Woo, colour!

[5lab]

TVs where so much easier to understand 30 years ago. Woo, colour!

but ntsc or pal or secam? *worry*

[Odc]

When I use my Xbox 360 at 1080i I notice that the text is less clear. That might just be my eyes playing tricks on me because of the things I've heard about interlaced but it could be true :s Also, while playing games I don't really notice any difference between 1080i and 720p so I just leave it on 720p because it seems to be the best resolution to use and you get a better frame rate.

[nvening]

I think that 1080i is i bad standard, its stupid if the screens cost more to make but have the same or worse image quality! Or am i missing something? Also loads of HDTVs have quite random resolutions, wont this make watching a 720p signal look not as good if scaled up or have black bits?

Infact, what effect of the image quality does scaling up and down have? We are always hearing about running LCD monitors at their native resolution.

Also someone mensioned that the signals we will get are not actually 720p and are just scaled to fit so are they not just makeing the image worse than it should be?

[Timmy!!!]

I have some questions:

720p = 720 horizontal lines, so why the hell do we get 768 lines? Is it cheaper because pc monitors have 768 lines so they can use these? When looking at HDTV's, there are no black bars at the top or bottom, so I am assuming that the picture is being stretched to fill all 768 lines. Wouldn't this cause fuzzyness and reduced picture quality? (this is also the case for the number of vertical lines - there are always more than the actual 720p HD resolution)