Before buying an HD display, read this lowdown on 720p vs. 1080i vs 1080p

Before buying an HD display, read this lowdown on 720p vs. 1080i vs 1080p

Summary: Last week (and just in time for any big holiday buying you plan on doing), David Carnoy who works over at one of ZDNet's sister organizations (within CNET) published what he's calling the final word on 720p vs. 1080p: the two "competing" resolutions for high definition (HD) television.

TOPICS: Hardware

Last week (and just in time for any big holiday buying you plan on doing), David Carnoy who works over at one of ZDNet's sister organizations (within CNET) published what he's calling the final word on 720p vs. 1080p: the two "competing" resolutions for high definition (HD) television. Carnoy's piece is an absolute must read for anyone considering the purchase of a high definition display because of how well he describes the various technologies and busts the myths around 1080p being better than 720p. Why is this important? Go to just about any electronics store today and you might see two flat panel LCDs that are side-by-side with each other that look identical (same manufacturer, same size, same bezel design, etc.) but that differ in price by several hundred dollars or more. Upon closer inspection of the fine print, you'll notice that one is rated for 720p and the other for 1080p. The big question is, should you pay more? (A question that wrongly answered "Yes" to when I recently bought my 42" HD flat panel). Writes Carnoy:

We still believe that when you're dealing with TVs 50 inches and smaller, the added resolution has only a very minor impact on picture quality. On a regular basis in our HDTV reviews, we put 720p (or 768p) sets next to 1080p sets, then feed them both the same source material, whether it's 1080i or 1080p, from the highest-quality Blu-ray and HD DVD players. We typically watch both sets for a while, with eyes darting back and forth between the two, looking for differences in the most-detailed sections, such as hair, textures of fabric, and grassy plains. Bottom line: It's almost always very difficult to see any difference--especially from farther than 8 feet away on a 50-inch TV....

....The extra sharpness afforded by the 1080p televisions he's seen is noticeable only when watching 1080i or 1080p sources on a larger screens, say 55 inches and bigger, or with projectors that display a wall-size picture. Katzmaier also says that the main real-world advantage of 1080p is not the extra sharpness you'll be seeing, but instead, the smaller, more densely packed pixels. In other words, you can sit closer to a 1080p television and not notice any pixel structure, such as stair-stepping along diagonal lines, or the screen door effect (where you can actually see the space between the pixels). This advantage applies regardless of the quality of the source.

Even though the headline of his story makes it sound as though it's primarily a discussion of 720p vs. 1080p, it's really much more than that.  Carnoy very authoritatively discusses the 1080i as well, describing in most excellent layman's terms what the difference between "i" and "p" are, what it means to you and me, and how many of the displays are capable of resolving differences between the resolution and type of signal being fed into a display and what the display is capable of (for example, feeding a 1080p signal into a 720 display).

What you don't get in this particular story of Carnoy's is a discussion of LCD vs. Plasma (or for that matter, the other display types such as CRT and DLP).  For that, I suggest checking out David Katzmaier's Four styles of HDTV (make sure you click through all the pages and check out the plasma vs. LCD table on the second page).

One rule of thumb that has suprisingly changed this year has been the maximum size of LCD flat panels.  In January, while at CES, we learned that except for Westinghouse which had gone LCD-only and was doing what it could to break the size barrier for LCD, pretty much all the major manufacturers had LCD's that went up to 47" in diagonal size and plasma displays that started at 42" in diagonal size and went up from there (some to more than 100 inches).  Already today though (as evidence of how quickly things are changing), all you need to do is visit your local electronics superstore to see LCDs from many of the majors that are 50-55 inches in size.

Speaking of shopping in superstores for these bad boys, one thing I've learned is that you don't want to eyeball the image quality of these displays in a typical showroom setting where florescent lighting is used.  Chances are that your viewing will involve incandescent lighting which, to the human eye, produces different results than florescent lighting when watching TV.  You're probably better off going to a home theater store that can reproduce the lighting situation you're most likely to use your TV in.

Topic: Hardware

Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.


Log in or register to join the discussion
  • Second Rule: Beware the Ringers

    [B]Speaking of shopping in superstores for these bad boys, one thing I?ve learned is that you don?t want to eyeball the image quality of these displays in a typical showroom setting where florescent lighting is used.[/B]

    The large vendors will take the time to optimize the display settings on the high end systems (and then put them in an optimal showroom). I seriously peeved a best buy employee by resetting the dazzling high end Sony ($2199) to default settings, making it look just as "average" as the same size/resolution Indignia. I then optimized the Insignia and guess what, it looked so much better tha the default Sony.

    No, don't buy Insignia, or not buy Sony, but just be aware, the more expensive machines are the ones tweaked out, you should check the settings.

    • Defaults favor fluorescent lighting

      One of the biggest bugaboos in consumer TV is "red push" - the tendency to increase red output to offset the effect that blue-white fluorescent bulbs tend to have - all in order to make them look better on a showroom floor under fluorescent bulbs. That's why when you get the set home (under incandescent lighting) the reds just overpower blues and greens. Ever notice how the picture looks in your favorite sports bar? Blame the excessive red saturation on "red push". Let's not even mention contrast and brightness just maxed out...

      The kicker? You can't adjust red push using the color/hue/tint controls. You have to get into the TV's service mode to adjust it. Think of it as dialing down the intensity of strictly the red gun in a CRT. You can check out sites like AVSForum or HomeTheaterSpot for instructions on adjusting it for different TV sets.
  • Huge difference in text quality

    ... and that's all I really care about.

    Try reading the same text on 720 that you do on 1080 and you'll go blind.
    Yagotta B. Kidding
    • I agree

      If the TV is less than 50", only the small text makes any difference.
      That begs the question why would you need such a huge and expensive monitor? ;)
      Linux Geek
    • No problem here...

      I have a 50" DLP at 720p. No text issues here. When I purchased this 2 years ago, I found that 720p on a DLP was superior for viewing sports (i.e. racing) programming over any 1080i display I saw. Zero blur...
      • 720p IS better than 1080i, but not 1080p...

        The post you responded to was saying that 1080 lines is better [u]for text[/u] than 720 lines. But your post was that 720 is better than 1080i? 1080i is effectively overscanned 540! Yes, 720 IS better than 540!

        And the post was also specifically about text, not motion. Small text, as when using the display as a computer monitor, not sports scores. Motion blur is more a factor of response times than resolution.

        People do use large displays as monitors. My display right now is running at 1920x1200, and it's only 24". Higher resolutions mean to me being able to see more of a spreadsheet at once. I do not want to run Excel with only 540 lines on my display, but 1080 is quite useable.

        So, whether resolution matters is largely, if not entirely, a factor of what you are using the display for. If you are sitting 8ft away watching sports on a 32" TV, the resolution won't make much difference. If you're 1ft away reading 8pt text on a 50" display, the resolution makes a world of difference.
    • Crank your font DPI

      It's what I do, works great.

      96dpi on a 37" 720p display (1280x720) looks crystal.
  • I honestly believe...

    That people who say they notice the difference on a 42" (or lower) 1080i vs 1080p are just fooling themselves.

    It's even a known thing in the industry that the only time you'll really notice the difference between 1080p on larger screens is if you're sitting closer than 7 feet otherwise you're eyes won't notice the difference.

    So why people are so focused on 1080p vs how far they actually sit. It boggles me people are willing to waste away money for absolutely nothing but to say to their friends. "I own a 1080p TV!".

    They knew which was the 1080p and 1080i get them to test a variety of TV's when they DON'T know the quality and watch how NONE of them will get it right.

    Put a Pioneer 1080i vs the Panasonic 1080p. Tell me which one is better? 9 times out of 10 people will say the Pioneer HAS to be 1080p when it actually isn't.

    People just love getting sucked into the Marketing machine.
  • Right for the wrong reasons

    I agree completely with Carnoy's apparent conclusion that most people probably can't see the difference between a 720p and 1080p screen of equal quality from 8 feet away. But that same observation holds for print from a 9 pin impact dot matrix printer and a laser printer when viewed from several feet away. You have to get close enough to see the extra resolution, and for a 50" screen, six feet is about optimal for a 1080p display. (See my book for a detailed explanation.)

    Alfred Poor
    HDTV Almanac
  • So Question for the experts

    My understanding is if I have 1080i HD but it supports 2:3 pulldown, doesn't that mean the what is shown is a frame (or 2) behind the actual live feed?

    If that is the case how is 1080i different from 1080p as my understanding is the way it is drawn from the feed onto the screen, however in 2:3 isn't it all cached in front and just displayed? So the interlaced vs progressive scan wouldn't mean anything (right?)
    • No

      From what I remember, 3:2 (not 2:3) pulldown helps with telecining original source of 24fps (frames per second) of movies shot on film to 60fps (fields per second) for video. Your 1080i set supports 30 frames / 60 fields per second, so its internal line doubler can basically "extract" (bad word, I know) the 24fps source and re-map it (AAABBCCCDDEEEFF - 3:2) to the 30 frames (1080 lines split into two interlaced fields of 540 lines each) per second. You still have 1080 total lines of resolution, but they're just written in two 540-line passes - two "fields" to make up one frame. Yeah - it's confusing.

      1080p is actually 1 frame per field - painted on a single pass, so if you were to hook up an HD/BluRay DVD player to your set, and watch original source material shot at 1080p, you'd only see every other frame. You still see the full 1080 lines of resolution, but only 30 frames per second rather than 60.

      Anyway - that's my story and I'm sticking to it! ;)
  • RE: Before buying an HD display, read this lowdown on 720p vs. 1080i vs 1080p

    Which January CES were you at? I was at the 1/07 CES in LV and saw two gorgeous 108" LCD displays from Sharp, who also showed several 65" units. Sony showed a 70" LCD. You made it sound like plasmas are bigger... not any more. The biggest plasma at CES was a 103" from Panasonic.
  • RE: Before buying an HD display, read this lowdown on 720p vs. 1080i vs 108

    If you are never going to watch HD or Blu Ray DVD's, then I agree that 720p is fine. HOWEVER......

    A bigger problem is that some of the advances that make a HD TV better - such as better blacks or higher scan rates - are only available in the newer 1080p sets.

  • 1080i hands down...

    "Why?" you ask? Simple, modern flat screen televisions, LCD, DLP and Plasma, cannot display an interlaced picture. Yep, they show a single frame full and complete one at a time without "scanning" like old TVs do. So the interlaced issue is not a real issue. 1080i is much less in terms of data and speed requirements from both 720p and 1080p that it will make both the sets and the signals cheaper and better to watch. the 1080p argument is null and void. Sure, 1080p will be much more widespread in the future, but right now 1080i is perfect for all modern TVs. And I dare you to show a visible difference between 1080i and 1080p on the same set. Try it, you won't see any difference.
    • ? CRTs came back....

      Hmmm my top end 32inch CRT still looks better on normal non HD tv to me than any lcd/plasma I have seen. I suspect we are all pushed into the flat screens as they are easier to make and ship plus they need to max that new factory..
      • You are correct.. it does look better depending on the HD set..

        Standard Def TV on a HDTV is generally crap. Because the HDTV is showing you all the flaws in the signal. I have however seen some HDTVs that do a great job with this but they are almost always DLP or CRT based. Because the manufacturer includes an analog component to display low res pictures rather than attempting digital conversion of the Standard def signal. Basically turning your expensive HDTV into a SDTV... However... if you simply refuse to watch SDTV you won't have this problem. Heck EVEN standard DVDs are 480p...which way better than standard def.. In most cases 480p vs. 1080i is a challenge to tell the difference in when the pictures are side by side....since 1080i is actually only 60 lines better...
    • Speed of Motion...

      The differences will become apparent only when viewing a subject which is moving quickly.

      In an interlaced ("i") mode, only half of the image is replaced in each update. If something is moving quickly, your eye just might notice that the odd lines in the display are out of sync with the even lines. When things move more slowly, this is harder to notice.

      In a progressive ("p") mode, the entire image is replaced every update. No matter how quickly things are moving, each image displayed is a complete, stand-alone image. This is much better with faster-moving subjects.

      It depends on the subject material being viewed.

      As for 1080 vs. 720, the differences will be more apparent as the size of the display grows. For a sufficiently small display, it won't be that big of a deal. Let the display size grow, and the difference will become more and more visible.

      A "p" mode is technically superior to an "i" mode, but for slow-moving subjects, and depending on the capabilities of the TV, your eye may not notice the difference. For faster-moving subjects, and particularly with larger screens, the difference becomes more noticeable.
  • new at hd

    most people dont have hd so any 720p or 1080p will be a big upgrade and be alots better picture. but a jump from 720 to 1080 would be very little of a upgrade.
    • It depends

      If using a large enough TV sure there is a difference.

      For smaller TVs the difference may not be very noticable.

      There would be little point in having an HDTV that was only 12 or 13 inches in size, for example...
  • There is no substitute for resolution

    The author can make all the subjective arguments he wants to justify 720p, 1080i etc. There is an old "video" engineering adage that "there is no substitute for resolution".

    Every time I have witnessed side by side 720p and 1080p [and I do it quite often] I am struck by the smoothness, as opposed to the sharpness, of the 1080p. As one earlier post mentioned you can see the differences in the diagonal edges of type. I can see it throughout the picture.

    One puzzling aspect of 1080 resolution in general, is the Consumer Electronics industry and the medias failure to review 1080 30p. That's right the folks who gave us all the HD standards made a provision early on for 1920x1080 pixel raster at a rate of 30 frames per second progressive.

    Since 30 frames is more than adequate to invoke persistence of vision we at Videography Lab believe that there should be serious dialog of 1080 30p as an acquisition and delivery standard for most [not all] content. 1080 30p delivers high resolution at half the bandwidth of 1080p. Do we really need 60 progressive frames per second for viewing movies and TV? Leave the really speedy stuff to the gamers.

    Of course, to view 1080 30p you have to have a 1080 Progressive monitor so my old Barco CRT is as good as a 720p monitor.

    There are many more steps to achieving User Generated Content in true HD that we'll be discussing at and some ideas we will relegate to it's companion site :)

    Bob Kiger
    Videography Lab