720p vs 1080i/1080p (1 Viewer)

[Doug MacGregor]

I'm close to buying a flat panel HD TV (within 6 months) and I need some basic advice.
The offerings now at some of the big box stores (Futureshop/BestBuy) are beginning to come down to my price range - less than $800 - and I can see the light at the end of the tunnel.
The least expensive ones (LCD) are the 720p models with the 1080i/1080p being at the top end.
What I need to know is...should I spring for the 720p models or wait until the 1080 models get even cheaper?
Will the 720p be good enough for SD DVD's and a satellite HD feed or will I even be able to tell the difference?
Thanks.

 

[JeremyErwin]

No. The very least expensive LCDs are not 720p or 1080i. They are 768p-- 1366*768, which means that every HD signal out there is upscaled or downscaled as appropriate.

Look at a cable box, or a bluray player sometime. You'll see options for 480i, 480p, 720p, 1080i, and 1080p. 768p is usually not among them-- which means that the opportunity for really sharp images is somewhat compromised.

However, most of the "768p" screens are rather small-- and unless you sit quite closely to them, you probably won't notice the "compromise", nor the extra detail that might be gleaned from a 1080p screen.

 

[Doug MacGregor]

Thanks Jeremy.
I was concerned that by jumping into a 720p right now (at 32 inches), I would be cutting myself off from a vastly superior picture for the next few years (I don't buy TV's very often).

 

[JeremyErwin]

There is one thing to watch out for-- and many of the cheaper sets skimp out on this.

Most televisions have a built in OTA-HD tuner. OTA sources are often better (at least in terms of picture) than what's available through cable or satellite. Some have a digital cable tuner as well, although the usefulness is disputable-- because cable companies want to rent you the box, and set their technologic standards appropriately.

But, sometimes these built in tuners lack an spdif or optical jack-- which means home theater owners can't enjoy the HDTV sound as it was meant to be heard-- dolby digital 5.1.

So, when you go shopping, be sure that your set has the appropriate jack, especially if you don't have HD cable/satellite.

 

[andrew markworthy]

It depends to some extent on the size of the screen - the difference will become more obvious the larger the display. But even on a smaller screen, yes, you would see a difference on occasions. For example, a classic example is aerial shots of cities - rows of windows in buildings in the background of the picture have a tendancy to 'strobe' on lower resolution sets. Now whether this is a deal-breaker is a matter of personal opinion. It tended to irk me until I upgraded to a Full HD set, but others may not be bothered. It's personal choice, period.

 

[Doug MacGregor]

Thank you all...I guess I'll wait until the 1080p prices come down.
Ii don't want to be stuck with a purchase I'll be sorry I made.

 

[andrew markworthy]

Given the way prices are falling, I seriously doubt if you'll have long to wait! In addition, round about this time of year (at least in the UK) the TV models change and often last year's models get sold off very cheaply. E.g. I just got a v. nice Full HD set (which was the european critics' favourite last year - not sold in the USA, so no point giving you the details) at under half price. As I said, it has the full HD specifications, plus one to one pixel matching (which I really wanted) 24 fps, etc. Worth thinking about looking for a similar deal in your neck of the woods.

Just one thing - this is probably preaching to the choir, but DON'T touch an ex-demonstration model unless you're being given it for free, preferably along with the private phone number of a hot lingerie model who is guaranteed to fulfil your every sexual whim and pay you for the pleasure. The damn thing will have been on at all day every day with every setting jacked up to maximum (the TV that is, not the lingerie model).

 

[Jeff Gatie]

Remember that it not only depends on the size of the screen, it depends on the size of the screen and the seating distance. The farther you get away from a screen of any size, the less you are able to distinguish between 1080p and 720p (you can't buy many 1080i screens today, they are older, mostly CRT technology). Here's a helpful chart that will help you optimize your screen size/resolution for your seating distance and budget:

 

[John CW]

From what I've read, it's often near impossible to tell the difference between 720 and 1080 on anything less than a 60" screen.

Also, isn't the "reference standard" Pioneer Kuro 768?

 

[andrew markworthy]

The differences on less testing pictures may not be as obvious, but nonetheless gains are to be had by going for the maximum resolution at any screen size.

So those owners of large screens who claim that only they can possibly be seeing true high definition in all its glory while we poor peasants with smaller screens cannot are, I'm afraid, talking a load of hot air. That doesn't mean that larger screens don't offer greater excitement, a bigger visual field, etc - of course they do. But that's only one aspect of viewing pleasure and has the downside that on anything other than a pristine source, the picture is going to look less than stellar. The reason I go to lengths to say this is that I fear that a lot of folks are being put off buying HD because they keep hearing this slogan of 'unless you've got a massive set, then don't bother' nonsense and are deterred, either because they can only afford a smaller set or their houses can only accommodate a smaller set.

 

[Jeff Gatie]

Whether you can see the difference between 720p and 1080p has nothing to do with screen size and everthing to do with the ratio of screen size to seating distance. The way this "you need at least XX inches" BS got started is because people buy the same size HD screen as their current SD screen and then watch it at the same distance as their SD screen. So of course you get no advantage. The consumer then thinks they have to move up to a 50" from their average size 32" SD in order to see a difference when they only have to sit closer to the 32".

By the way Andrew, the chart is based on the the fact that with 20/20 vision it is possible to resolve 1/60th of a degree of an arc; i.e. the "physical" capabilities of the human eye. The "psycho" part is up to the individual, taking into account things such as their room decor, ambient lighting and whether they were raised under a stifling class system that considers any TV display over 32" as ostentatious (a sin punishable by death or banishment).

 

[John CW]

All I've got is your word. According to the chart, and you sit 8 feet away from your TV, you won't be able to physically see the difference on a 42" set. On a 32" set you'd have to sit 3 to 4 feet away... Which is FAR too close for me (I don't know about anyone else.)

There must be an *average* distance-from-TV that consumers have (between 8 and 12 feet or something). Given that, whatever the number is, it's fair to say that most consumers won't see a difference unless their TV is of a particular size.

It's certainly something people buying new TVs should factor in.

Let me ask you one question: Have you compared two 42" TVs of the same make, same generation, both running the same film? But one with 768p and one 1080p?

If not, how can you say with any certainty that there's a visible difference when sitting at a comfortable distance?

 

[JeremyErwin]

Contrast ratio (so to speak) is often more important than resolution-- and that's where the Kuro excels. If the scene is of an inky black sky lit up by the milky way, it really doesn't matter that the LCD has more pixels-- the scene looks more realistic on a plasma.

1080: 1920 horizontal pixels, 32 degrees of arc
768: 1366 horizontal pixels, 22 degrees of arc
720: 1280 horizontal pixels, 21 degrees of arc
480: 720 horizontal pixels, 12 degrees of arc.

If the screen only occupies 20 degrees of arc, odds are that your eyes aren't good enough to see any benefit to 1080p.

 

[Jeff Gatie]

Saying the difference can't be seen at certain distances does not mean there is no difference. There most certainly IS a difference between 1080p and 720p, from the smallest of screens up to the largest front projection. 1080p allows you to sit closer to a same size screen or get a bigger screen for the same viewing distance and not be able to distinguish the individual pixel elements. Putting your personal viewing tastes; i.e "comfortable distance", and room dynamics on the equation does not make the generic statement that "it's often near impossible to tell the difference between 720 and 1080 on anything less than a 60" screen" any more correct.

You are correct when you say this is something people buying new TV's should factor in. They should also factor their budget, preferred display type, and seating distance. As I've told people before - Screen Size, Price, Display Type, Seating Distance - You get to pick 3, the 4th one you have to swallow.

One more thing, yes I have compared 2 42" displays, one 720p and one 1080p. At 9' there's no real difference. At 5', there's a big difference. That's why I sit 8' from a 65" 1080p DLP.

 

[DaveF]

Dubious about Jeff's chart at first, I did a quick calculation (before seeing this comment) assuming 1 arc-minute angular resolution, which is standard resolution number for human vision and sure enough I find that you need about a 130" diagonal TV seen from about 15-feet for 1080p to be discerned. That's right in with the chart's values (it gives about 120", so it's definitely using a 1-arcmin assumption.)

This is quite interesting. The 1-arcmin resolution is (I believe) best resolution (foveal vision) for a high-contrast (black and white bar), stationary target. Actual visual discernment will vary with lighting (low contrast or similar colors), motion (moving picture), peripheral vision, and vision correction (what, you don't have 20/20 vision?).

Nuts and bolts -- it could be that many people can't tell the difference between 480p and 1080p for typical setups, like a 50" to 60" HDTV watched from 12' to 16' away. Frankly, most people are probably better off with a 720p set to balance finances versus real image improvement.

I wish I still had easy access to the research journals on vision science as it would be interesting to check for relevant research.

 

[andrew markworthy]

In fact, the two are combined in psychophysics to create the contrast sensitivity function. Basically, this plots the JND (in this instance where you can first accurately discern a pattern of black and white parallel lines) on a graph with line thickness on one axis and contrast level on the other. The greater the contrast, the thinner the lines can be for to there to be a JND (and similarly, a coarser pattern enables there to be less contrast). So yes, contrast is important in discerning pattern. And as you get older, contrast sensitivity significantly worsens. This is often why if you visit an older person's house, their TV seems overlit and garish - for them, it looks right.

 

[Jeff Gatie]

Dave,

Here's the article where I first saw that chart (it's been all over the net since):


Which is exactly what we've said in this thread.

 

[andrew markworthy]

To quote from the site Jeff provided a link to:


Or in other words, plasma has a superior picture, but you can't see it.

 

[DaveF]

Yes, that chart is based on the commonly used seeing resolution limit of 1 arcmin.

This chart is a back-of-the-envelope estimate. But what catches me is that it might still be too optimistic for many people -- whereas you, Andrew, are saying it's too pessimistic.

When the time comes to buy a new HDTV, I look forward to "testing" these factors

 

[John CW]

Andrew is clearly very cynical about anybody saying that 1080p might not be visibly different. The problem is that he doesn't actually have any arguments other than his cynicism. The counter-arguments however, have scientifically based testing behind them.

So I guess it's up the reader what you go for: Baseless cynicism or scientifically based research. Hmmm.