| 1080p HDTV Sets have started to emerge. Should you opt for o |
| by: Andrew Ghigo |
1080p HDTV sets are capable of spectacular results, but
they cost substantially more. 1080p HDTV – also referred to as
ultra-HDTV - 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, in order to help you get a better understanding of
the strengths and weaknesses of each.
It is all an issue of Image Resolution
There are currently three different HDTV formats: 720p, 1080i,
and 1080p; all three are designated as HD-Digital TV standards
by the Advanced Television Systems Committee (ATSC),
which adopted these formats.
The main difference between these three HDTV formats is 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 by 1080 lines. In other words, both
support the same image resolution but there is a significant
difference in the way the 1080i (interlaced) and the 1080p
(progressive) formats build up the image.
Surely, 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 or
full-HD by some manufacturers ...but there is a price to pay to
get the latest in HDTV technology.
On the other hand, the way the 1080i and the 720p formats build
up the image may render the lower resolution 720p format more
suitable to display certain image content.
In other words, do not simply jump to conclusions as to which
HD format is best. As we will see in this article, each of these
different HDTV formats has got its strengths and weaknesses.
1080i: 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) - by
first painting all 540 even-numbered lines on the screen (also
referred to as the even-field), and then proceed with the
painting of the odd-numbered lines (odd-field). These two fields
together form a single frame of 1080 lines.
In the process, the screen is painted 60 times per second (50
times in a PAL signal) - each time painting only half of the
lines per frame, with the entire screen being painted in two
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 1/60th of a second out-of-synch with
the next or previous line. This in itself will impact on the
type of image content that is best displayed on an interlaced
display.
720p and 1080p HDTV: In contrast, in progressive-scan
formats - 480p (EDTV), 720p and 1080p HDTV displays - all
scanning lines in a single frame are displayed sequentially in a
single pass.
In the process, a progressive scan video format writes one full
frame of video information every 1/60 of a second as against the
1/30th of second required for an interlaced format.
The Bottom Line
The 1080i format is more widely supported by manufacturers and
broadcasters; broadcasters however would normally broadcast only
in either 720p or 1080i but not both. This should not be much of
an issue in that any HDTV set you buy should be able to display
pictures in any HDTV format by up-converting or down-converting
to its native format, i.e. the one in which it\'s designed to
produce a picture.
From a pixel-count perspective, the 1080i supports better
spatial resolution than a 720p HDTV display. In fact, while a
1080i supports a total pixel count of 2.07 million pixels, a
720p display supports only 0.92 million pixels. This means that
if you want to display a 1080i signal on a 720p screen, you will
lose 55.6% of pixels information.
This is not the case with 1080p HDTV which supports the same
spatial resolution as 1080i, but with the added benefit that all
1080 scanning lines are displayed in a single pass, 60 times per
second.
In other words, 1080p HDTV combines the superior resolution
of the 1080i format with the progressive-scan smoothness of 720p
HDTV.
Because of the two passes per frame in a 1080i signal, a 1080i
HDTV display is capable of producing a sharper picture only when
the image is frozen or barely moving.
Progressive-scan 720p and 1080p HDTV displays introduce fewer
motion artifacts, such as jagged diagonal lines and movement in
fine detail, into the picture, leading to a video image that
looks smoother and that stays sharper during motion than an
interlaced one.
This means that a 720p display - with its substantially lower
picture resolution, need not necessarily be worse than a 1080i
one. Theoretically, a 720p display should be capable of a better
flicker-free picture when it comes to fast moving action movie
scenes and sports.
In comparison to the other two HDTV formats, 1080p HDTV has the
best of both worlds - it has the spatial resolution of a 1080i
signal and the smooth stable image of a progressive scan format.
It is worth mentioning here that interlaced formats aren\'t
really an option in fixed-pixel displays (DLP and LCD
rear-projection as well as plasma and LCD flat-panel). This also
explains why display manufacturers are shifting away from the
1080i and instead moving directly from 720p to 1080p HDTV.
And What about 1080p HDTV Sets?
Surely, 1080p HDTV represents the latest developments in HD
Television technology. A few of these sets have already started
to hit the market.
Among the latest HDTV models released this year, one can find
the much awaited Samsung\'s 2005 line-up of DLP 1080p HDTVs.
Not surprisingly, these sets do not come cheap. There is a
premium one has to pay to get the latest and best in the HDTV
world. As a minimum, expect to pay at least $1,000 to $2,000
more to jump from a 720p to a 1080p HDTV display. But when you
are spending some $3,000 plus for a HDTV set, it is only human
that you will be ready to fork out another one or two thousand
dollars to get the best of breed.
Should you opt for a 1080p HDTV Set, and are these sets 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:
- Surely, these sets are capable of producing spectacular
results with ultra sharp images. But whether you will be able to
see the difference in image quality between a 720p display and a
1080i signal displayed on a 1080p HDTV display depends on your
TV viewing distance and screen size, more than on the screen
native resolution. (It is not the scope of this article to
discuss the TV viewing distance but more info in this respect is
available at our site at
http://www.practical-home-theater-guide.com/Tv-viewing-distance.h
tml)
- In reality, it would be very difficult to detect any
difference in image detail between 720p and 1080i/p HDTV
material on the smaller sets from 10-feet away. Sit closer and
feed your 1080p HDTV set with a good quality HD source, and you
will start to see the difference.
- Further more, with most of today\'s HD broadcasts, you\'ll be
hard pressed to see a difference in picture quality when you
compare the image on current 720p sets versus the latest 1080p
HDTV models. Surely, if you are thinking of going really big,
then the extra image resolution would make the difference. But
keep in mind that at present, true 1080p HDTV material is almost
non-existent. What\'s more, none of the major networks has
announced 1080p broadcasts. If and when such high-def formats as
\'Blu-ray\' or \'HD-DVD\' take off, the equation may change. But it
will probably be at least a few years from now before this stuff
become truly within reach of many household budgets.
Finally, most 1080p HDTV sets presently available on the
market do not offer a 1080p connection. Though the HDMI standard
does support 1080p HDTV, yet the majority of today\'s 1080p HDTV
sets do not offer a 1080p connection on their HDMI port.
To a certain extent, this is explained by the lack of true 1080p
HDTV gear with which these sets can interconnect. In fact, what
1080p sets do is to up-convert 1080i material to 1080p HDTV to
combine the benefits of a superior resolution of the 1080i
format with the image smoothness and motion sharpness of
progressive-scanning.
(c) 2004/2005 http://www.practical-home-theater-guide.com.
All rights reserved.
This article is an excerpt from a series of guides appearing
under the Rear Projection TV Reviews section of the site.
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