Jump to content



Sign up for a free account!

Signing up for an account is fast and free. As a member you can join in the conversation, enter contests to win things like this Logitech Harmony Ultimate Remote and you won't get the popup ads that guests get. Click here to create your free account.

Photo
- - - - -

720p vs 1080i/1080p


  • You cannot start a new topic
  • Please log in to reply
37 replies to this topic

#1 of 38 Doug MacGregor

Doug MacGregor

    Stunt Coordinator

  • 84 posts
  • Join Date: Nov 23 2002

Posted March 17 2008 - 05:11 AM

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.

#2 of 38 JeremyErwin

JeremyErwin

    Producer

  • 3,219 posts
  • Join Date: Feb 11 2001

Posted March 17 2008 - 05:45 AM

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.

#3 of 38 Doug MacGregor

Doug MacGregor

    Stunt Coordinator

  • 84 posts
  • Join Date: Nov 23 2002

Posted March 17 2008 - 07:11 AM

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).

#4 of 38 JeremyErwin

JeremyErwin

    Producer

  • 3,219 posts
  • Join Date: Feb 11 2001

Posted March 17 2008 - 07:24 AM

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.

#5 of 38 andrew markworthy

andrew markworthy

    Producer

  • 4,766 posts
  • Join Date: Sep 30 1999

Posted March 17 2008 - 08:37 AM

Quote:
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?
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.

#6 of 38 Doug MacGregor

Doug MacGregor

    Stunt Coordinator

  • 84 posts
  • Join Date: Nov 23 2002

Posted March 17 2008 - 11:32 PM

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.

#7 of 38 andrew markworthy

andrew markworthy

    Producer

  • 4,766 posts
  • Join Date: Sep 30 1999

Posted March 18 2008 - 05:24 AM

Quote:
Thank you all...I guess I'll wait until the 1080p prices come down.
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).

#8 of 38 Jeff Gatie

Jeff Gatie

    Lead Actor

  • 6,529 posts
  • Join Date: Aug 19 2002

Posted March 18 2008 - 06:58 AM

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:

Posted Image

#9 of 38 John CW

John CW

    Supporting Actor

  • 619 posts
  • Join Date: Oct 07 2000

Posted March 19 2008 - 01:20 PM

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?
Alphabetti Spaghetti

Elvis returns from the dead to say: "Objectively looking at the world, you're the only people alive on the earth today. All the people who created tradition, created countries, created rules ... THEM #@&%ERS ARE DEAD. Why don't you start your own world while you got the chance?"

#10 of 38 andrew markworthy

andrew markworthy

    Producer

  • 4,766 posts
  • Join Date: Sep 30 1999

Posted March 20 2008 - 01:14 AM

Quote:
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.

I'd love to know where this got established as fact, as it's plain wrong. The facts of the matter are:

(1) the bigger the screen the more obvious the difference between 720 and 1080, i versus p, etc. But that doesn't mean you can't see a difference on smaller screens as Jeff's graph helpfully points out (though with respect, this looks like an idealised graph rather than one based on real psychophysical data).

(2) You can most definitely see a difference on smaller screens. As I stated in the post above:
Quote:
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.
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.

#11 of 38 Jeff Gatie

Jeff Gatie

    Lead Actor

  • 6,529 posts
  • Join Date: Aug 19 2002

Posted March 20 2008 - 02:00 AM

Quote:
Originally Posted by 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?

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). Posted Image

#12 of 38 John CW

John CW

    Supporting Actor

  • 619 posts
  • Join Date: Oct 07 2000

Posted March 20 2008 - 05:47 AM

Quote:
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.

Quote:
Originally Posted by andrew markworthy
I'd love to know where this got established as fact, as it's plain wrong.

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?
Alphabetti Spaghetti

Elvis returns from the dead to say: "Objectively looking at the world, you're the only people alive on the earth today. All the people who created tradition, created countries, created rules ... THEM #@&%ERS ARE DEAD. Why don't you start your own world while you got the chance?"

#13 of 38 JeremyErwin

JeremyErwin

    Producer

  • 3,219 posts
  • Join Date: Feb 11 2001

Posted March 20 2008 - 06:40 AM

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.

#14 of 38 Jeff Gatie

Jeff Gatie

    Lead Actor

  • 6,529 posts
  • Join Date: Aug 19 2002

Posted March 20 2008 - 07:47 AM

Quote:
Originally Posted by 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?

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.

#15 of 38 DaveF

DaveF

    Moderator

  • 13,060 posts
  • Join Date: Mar 04 2001
  • Real Name:David Fischer
  • LocationOne Loudoun, Ashburn, VA

Posted March 20 2008 - 08:56 AM

Quote:
Originally Posted by Jeff Gatie
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.
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.

#16 of 38 andrew markworthy

andrew markworthy

    Producer

  • 4,766 posts
  • Join Date: Sep 30 1999

Posted March 20 2008 - 09:00 AM

Quote:
All I've got is your word. According to the chart,
And as I said, I'd love to see the data behind that chart - they look like extrapolations from basic geometric calculations. Very happy to be corrected, but I don't think they are based on psychophysical measurements.

And as regards 720 v 1080 displays, no I haven't tested two screens side by side (unwise anyway, since unless you know every single component inside the sets is the same, even if they are ostensibly the same model, it's a waste of time). However, I have compared the same set on different settings using a very objective measure of how much 'shimmer' can be seen on narrow parallel line patterns. And the simple fact is that 1080 outranks 720 on this measure since patterns that cause no shimmer at 1080 do cause shimmer at 720. This applies at any distance and on any but the tiniest of screens, until you get far enough away from the screen that the lines blur into gray (and this is further away than recommended viewing distances). This is a nice neat test that anyone with a suitable set, high def player and calibration disc can try for themselves. And there is no getting out of this - there really is a difference. If you haven't got a high def player or calibration disc, the best thing to do is record a program with some helicopter shots of a city scene and watch the windows in the buildings in the distance for shimmer at 720 and 1080. There will be more shimmer at 720. This is an inescapable feature of image resolution and will be noticeable at any sane viewing distance.

For normal everyday viewing, this distinction won't mean much because we don't spend much of our lives gaping at patterns of parallel lines, but for any comparison to be meaningful, it has to look at JNDs (just noticeable differences) and that means pushing things to the limit. So although I've said there is a difference, and it's noticeable, for the majority of the time it really won't matter, and certainly if you're an average viewer who just wants to flop in front of the TV and watch the program rather than obsess about the picture quality, the 720 v 1080 issue is probably largely academic. And I for one wouldn't knock that - 720 resolution still looks great, and the improvement that 1080 brings is marginal (it's not that 720 is twice as good as SD and 1080 is twice as good again). I certainly wouldn't want to deter anyone with 720 to think they're missing something really important, because they're not. However, if we want to push things to an extreme, the difference really can be seen in extreme circumstances on all sets. But it's unlikely to be more than a trivial issue until you get to really massive screens, which as I said earlier, not everyone can have or even wants. [This isn't a dig at those with larger screens - I can afford one, thanks very much, so I'm not consumed by envy, but it just wouldn't suit the room we watch TV in.]


Quote:
Contrast ratio (so to speak) is often more important than resolution
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.

#17 of 38 Jeff Gatie

Jeff Gatie

    Lead Actor

  • 6,529 posts
  • Join Date: Aug 19 2002

Posted March 20 2008 - 09:09 AM

Dave,

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

Quote:
1080p Does Matter - Here's When (Screen Size vs. Viewing Distance vs. Resolution) » CarltonBale.com

He gives his methodoolgy for his estimations. Also usefull to this thread is the following quote:

Quote:
In conclusion: If you are a videophile with a properly setup viewing room, you should definitely be able to notice the resolution enhancement that 1080p brings. However, if you are an average consumer with a plasma on the far wall of your family room, you are not likely to be sitting close enough to notice any advantage. Also, the Imaging Science Foundation (ISF) states the the most important aspects of picture quality are (in order): 1) contrast ratio, 2) color saturation, 3) color accuracy, 4) resolution. Resolution is 4th on the list and plasma is generally superior to LCD in all of the other areas (but much more prone to reflections/glare.) So pick your display size, then measure your seating distance, and then use the charts above to figure out if you would benefit from the larger screen size.

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

#18 of 38 andrew markworthy

andrew markworthy

    Producer

  • 4,766 posts
  • Join Date: Sep 30 1999

Posted March 20 2008 - 08:48 PM

To quote from the site Jeff provided a link to:

Quote:
Based on the resolving ability of the human eye (with 20/20 vision it is possible to resolve 1/60th of a degree of an arc), it is possible to estimate when the differences between resolutions will become apparent.

It's as I thought - extrapolations from basic geometry. This is fine as a rough guide, but as I've been saying, probably doesn't totally match human viewer experience.

Jeff, much as I agree with the spirit of what you've said, I had a chuckle over my breakfast cereal reading the second quotation (yes, I am sad enough to eat breakfast whilst sitting at the computer).

Re: the Imaging Science Foundation statement, I'd love to know how one can prioritise necessary factors. It's like saying 'the How To Stay Alive Foundation states that breathing is more important to staying alive than your heart beating'. It's meaningless. And I love the shooting oneself in the foot statement after the portentious technical pronouncement:


Quote:
plasma is generally superior to LCD in all of the other areas (but much more prone to reflections/glare.)

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

#19 of 38 DaveF

DaveF

    Moderator

  • 13,060 posts
  • Join Date: Mar 04 2001
  • Real Name:David Fischer
  • LocationOne Loudoun, Ashburn, VA

Posted March 21 2008 - 12:46 AM

Quote:
Originally Posted by andrew markworthy
It's as I thought - extrapolations from basic geometry. This is fine as a rough guide, but as I've been saying, probably doesn't totally match human viewer experience.
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 Posted Image

#20 of 38 John CW

John CW

    Supporting Actor

  • 619 posts
  • Join Date: Oct 07 2000

Posted March 21 2008 - 12:46 PM

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.
Alphabetti Spaghetti

Elvis returns from the dead to say: "Objectively looking at the world, you're the only people alive on the earth today. All the people who created tradition, created countries, created rules ... THEM #@&%ERS ARE DEAD. Why don't you start your own world while you got the chance?"


Back to Display Devices (TVs/Projectors/Screens)


0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users


Forum Nav Content I Follow