1080p HDTV Sets are flying off store shelves... Should you opt for One?

A Guide to HDTV Formats

1080p HDTV, 1080i or 720p? 1080p represents the latest in a series of HDTV video formats. With a variety of formats to choose from, things for the HDTV buyer may start to get confusing.

In this article, we discuss the differences between 720p, 1080i, and 1080p HD formats. In the process, we see how these differences impact image quality. We also explain when it makes sense to opt for the higher-end and more expensive 1080p TV set.

An affordable  top-performer: Samsung LN52A650 52-inch 1080p 120Hz LCD HDTV

1080p HDTV... the hot spec of the moment!

The ECA (Electronics Consumer Association), estimated that by end 2007, there were more than 60.6 million HDTV sets in U.S. households.

This represents an HD penetration of 36% among all U.S. households. Equally important, one-third of these HD households had multiple HDTV sets; in most cases, the second or third HDTV set is a 1080p television.

It is the drastic fall in prices of HDTV sets we have seen during 2007 that has led to a sharp increase in the presence of HDTV sets, and in particular of 1080p TVs.

And according to a report by DisplaySearch, it is expected that the 1080p high definition TV will outsell 720p HDTVs within the coming months.  

This despite the higher price tag and - equally important - the non-availability of broadcast programming in 1080p! In fact, the only commercially available 1080p video content comes in the form of high-definition discs from Blu-ray and HD DVD.

The irony is that notwithstanding the increase in the presence of HDTV sets in US households, there is still a lot of consumer confusion about high definition television.

A survey conducted by Best Buy in 2007 revealed that having an HDTV set in the house does not necessarily imply the consumer has an understanding of HDTV.

89% of all consumers participating in the Best Buy survey stated they lack the necessary understanding of HDTV technology, while half of all HDTV owners admitted they are either not watching HD programming, or are not sure if they are!

The unfortunate thing is that TV makers appear to be taking a ride over this lack of consumer understanding. They are pushing ahead the more expensive 1080p HD set even at screen sizes where difference in picture detail between a 720p and a 1080p image would be unperceivable.

There is a very simple reason for this drive by TV makers - 1080p sets carry a higher price tag and therefore a higher profit margin.

To justify this move, TV makers and retailers alike profess to the world that 1080p HDTV sets deliver better resolution than 720p HDTVs and improved performance over 1080i.

The average TV consumer does not have an understanding of the differences between the different HDTV formats, and therefore is ready to pay the higher price tag associated with 1080p HDTVs to get the 'better TV'.

It is true that a 1080p HDTV delivers improved picture resolution, but...

This article was originally published in mid-2005 when the first 1080p HDTV sets started to appear on store shelves; it was then revised later in May 2006. It was a time when you had to spend anything between $1000 and $1500 to make the jump to what represents the gold standard in HDTV. And this to get a 1080p HDTV that in most cases did not even support a 1080p input!

Technology has changed a lot since then. Not only all present HDTVs - irrespective of format - support a 1080p input,   HDTV sets have become much better, bigger, and equally important, significantly cheaper. And what started as 1080i vs. 1080p is now 720p vs. 1080p. This new write-up reflects this changing environment in high definition television.

It is all an issue of 'Image Resolution'

There are currently a number of different HDTV formats as adopted by the Advanced Television Systems Committee (ATSC), based on 720p, 1080i, and 1080p - using refresh rates that vary between 24 Hz and 60 Hz.

The basic difference between these HDTV formats is mainly one of image resolution. The 720p is on the lower-end of the scale with an image resolution of 1280 pixels by 720 lines. The other two formats both support 1920 pixels horizontally by 1080 lines vertically.

In other words, both 1080p and 1080i support the same theoretical image resolution. However, there is a significant difference in the way the 1080i (interlaced) and the 1080p (progressive) formats build up the image.

Image resolution in fixed-pixel displays is a very HOT topic with many HDTV buyers. For many, the obvious choice is to opt for the latest 1080p HDTV - also referred to as ultra-HD, full-HD or higher HD by some manufacturers. But as expected, there is a price to pay to get the latest in HDTV technology.

On the other hand, the way 1080i and 720p formats build up the image may render the lower resolution 720p format more suitable to display certain image content.

So... do not simply jump to the conclusion as to which HD format is best; each of these formats has its strengths and weaknesses.

1080i HDTV

Up to a few years ago, this was considered as the reference standard in HDTV. Nearly all first-generation HDTVs were rear-projection sets that supported this standard. This format boasts a picture resolution of 1920 pixels by 1080 horizontal lines that are painted on the screen in two interlaced halves (hence the 'i' in the '1080i' format). It first paints all 540 even-numbered lines on the screen (this is referred to as the even-field), and then proceed with the painting of all 540 odd-numbered lines (or odd-field). These two fields together form a single image frame of 1080 lines.

This process is repeated 60 times per second - each time painting only half of the lines per frame. This means that the entire image is painted on the screen in two separate passes, 30 times every second.

Because of the way the interlaced process paints the screen, all picture information contained in adjacent odd and even lines in an interlaced image is 1/60^th of a second out-of-synch with the next or previous line. The image difference between the two halves of the picture would show up in what are referred to as 'interlaced artifacts'. Not much of an issue with slow-moving or static content, but these artifacts would become more pronounced with fast moving objects. This in itself will impact on the type of image content that is best viewed on an interlaced display.

720p and 1080p HDTV

In contrast, all progressive-scan formats - 480p (Enhanced-DTV), and 720p high definition TV, and 1080p HDTV - display each individual line sequentially in a single pass to build up the complete frame. This means that in progressive scan video, image information between adjacent lines is displayed in a 'more correct, timely manner'. This makes progressive scan capable of delivering a smoother, cleaner image, especially with sports and other motion-intensive content.

Effective Resolution: 720p, 1080i, 1080p - Which is Better?

720p vs. 1080i

TV stations would normally broadcast only in either 720p or 1080i but not both; the predominant format is 1080i. This in itself is not an issue; all present HDTV sets can display pictures in any HDTV format by up-converting or down-converting to the set native format, i.e. the one in which the set is designed to produce a picture.

Theoretically, from a pixel-count perspective, 1080i supports better spatial resolution than a 720p HDTV. In fact, 1080i supports a pixel count of over 2 million pixels as against the 0.92 million pixels supported by 720p HDTV but...

In reality the situation is somewhat different when it comes to an interlaced format. As expressed earlier on, the differences between the two halves of an interlaced image lead to interlaced artifacts. In order to reduce the visibility of these artifacts, the vertical resolution of an interlaced signal has to be filtered. That reduces the real image vertical resolution far below the number of scan lines (typically 60% of the number of lines) associated with the interlaced format. Furthermore, 1080i material is limited to around 1440 pixels horizontally; this reduces the overall effective resolution of the 1080i format to around 0.93 million pixels.

It is thus clear that the actual difference in effective resolution between 720p and 1080i is almost negligible. And this apart from the fact that a 720p display is capable of a better flicker-free picture when dealing with fast moving action movie scenes and sports.

Yet there is another issue against interlaced video, that of digital compression of images. Digital image compression is more efficient with progressive video at the source than interlaced video. Digital TV broadcast uses the same 6MHz maximum allocated broadcast bandwidth as with standard definition analog TV. This means that it is necessary to apply compression to make high definition images fit into the space allocated for a broadcasting TV channel. 

And what about 1080p HDTV?

The situation with 1080p HDTV is totally different. The horizontal resolution of 1080p HDTV material is equal to the number of scan lines since there is no need to reduce this as in the case of interlaced material. This means that 1080p supports the full 2.07 million pixels (1920 x 1080 pixels), as against the effective 0.93 million pixels in 1080i video and 0.92 million in 720p HDTV. And this apart from the added advantage that 1080p enjoys over 1080i in that all 1080 lines are displayed in a single pass.

In other words, 1080p HDTV enjoys the best of both worlds - it has the spatial resolution of 1080i HDTV material and the smooth stable image of a progressive scan format. It is a case where if you want the very best in high definition television, then 1080p HDTV is the way to go, but...

As things stand today, there is no 1080p HDTV broadcast and there is little chance that broadcasters will jump to 1080p any time soon due to bandwidth limitations. Even high-definition games on the Xbox 360 and PlayStation 3 are usually 720p, though the user can upscale these to 1080i or 1080p in the console user settings. The only way you can get hold of true 1080p HDTV commercially available content - apart from hooking your PC to your HDTV set, is via an HD disc - using a Blu-ray player (or the now almost defunct HD DVD disc). The large majority of high definition discs are natively encoded in 1080p while all the latest high definition players support 1080p output.

Apart from CRT, interlaced formats are not an option with fixed-pixel displays, namely microdisplay based DLP and LCD rear-projection systems as well as plasma and LCD flat-panel sets. All microdisplay based TVs are essentially progressive-scan technologies, so when presented with interlaced video (480i or 1080i), they convert it to progressive-scan for display. This explains why manufacturers are shifting away from 1080i and instead moving directly from 720p to 1080p HDTV.

Yet there is another important issue here and that is specific to all fixed-pixel displays. These displays will have to convert incoming video - irrespective of format or resolution, to the screen native resolution. The process involves upconverting or downconverting the video resolution to match that of the display; in the case of interlaced video, it also involves deinterlacing. These processes can introduce errors that are often overlooked by the HDTV buyer despite that these may impact picture quality. Unfortunately, how well an HDTV set scales an image or deinterlace video content is  not something one can put in the set specifications list.

1080p HDTV Sets

The 1080p HDTV set has become more widely available than its 720 counterpart as manufactures are mainly focusing their TV line-ups on 1080p sets. However, there is a premium one has to pay to get the latest and greatest in the HDTV world. 1080p HDTV sets do not come cheap; at present, the price gap between a 720p and a 1080p set hovers around $500 to $700. Still, this contrast heavily from an average of $1,500 to $2,000 when the first 1080p sets appeared on the market in around 2005.

	Sets such as the Panasonic Viera TH-50PZ80U 50-inch 1080p plasma HDTV released earlier this year, is selling at amazon for around $2050. In contrast, a 720p equivalent from the same Panasonic line-up, the Viera TH-50PX80U is selling at $1450.

The Panasonic TH-50PZ80U is a top-seller among plasma HDTVs. Apart from the sleek styling,  the TH-50PZ80U can produce one of the deepest shades of black, excellent color accuracy, and come with a relatively effective antireflective screen.

Similarly, the Samsung LN46A650 46-inch 1080p 120Hz LCD HDTV is another great performer among the latest HDTVs. Apart from that unique red touch, you will get a 1080p LCD HDTV with superb black-level performance, highly accurate color, improved 120Hz de-judder video processing, and last but not least, you also get a broad selection of picture setup options. This Samsung 1080p HDTV is selling at $2300, that's $600 more than a 720p version from the same 2008 Samsung line-up.

What about 'bargain' 1080p HDTVs?

Well, if you want to get hold of a top-performer from one of the leaders in the field at a truly affordable price tag, your best option is to go for one of the top models from 2007.  Top-performers from 2007 line-ups include the Sony Bravia KDL-46XBR4 LCD HDTV and the Samsung FP-T5084 50-inch 1080p Plasma HDTV, both of which can still be obtained at substantial discounts. These sets represent a worthy investment in high tech despite not being the very latest in 1080p HDTVs. For our detailed reviews of these HDTV sets, check here: Sony KDL-46XBR4 and Samsung FP-T5084.  

1080p Sets - Bigger, Better, and Cheaper

The reality is that a lot has changed since the first 1080p HDTV sets appeared on the market. Not only HDTVs have become bigger, better, and sharper, they have also become significantly cheaper, and what once represented the unattained dream for the average home theater enthusiast, has now become a rather common reality.

As indicated earlier on, the 2007 was characterized by a sharp fall in the prices of HDTVs - and in particular of 1080p HDTVs. This trend is expected to continue during 2008, though a new CNN/Money report says that HDTV prices may be rising soon - probably sometime during the holiday season - due to the weak U.S. dollar, record fuel prices and escalating Chinese production costs.

In any case, HDTVs will continue to remain affordable, while consumers will continue with their present trend of buying a second - and possibly a third - HD television, and most probably this HDTV set will be a 1080p HDTV.

The Bottom Line: Should you opt for a 1080p HDTV?

When is a 1080p TV worth the extra expense? Well, there is no straight answer here. It all depends on what are your requirements, yet there are a few facts you should know before making any decision:

Nevertheless, the whole equation in favor of 1080p HDTV sets is changing fast. The marginal difference in price between 720p and 1080p HDTV sets is making the 1080p HDTV set more of a real option - especially if you want to have the latest and best spec in HDTV.

And the 1080p option would make even more sense if you plan to go really big. Consider a 1080p HDTV for anything bigger than 52-inch - especially if you have a good quality 1080i or 1080p HD source and plan to sit closer to your TV than twice the screen width.

Similarly, go for a 1080p HDTV if you plan to use your TV as a big computer monitor. Though icons and text may appear too small on a 1080p TV, and you may have to re-scale the desktop to fit, yet a 1080p set gives you some added flexibility when it comes to computer connectivity.

If none of these issues represent a priority, or are working on a tight budget, then you may very well do your bank account a favor and get a 720p HDTV; high definition content will still look great!

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