HDTV (High-definition television)


hdtv.jpgHDTV (High-definition television) was started in 1970 by NHK (Japan Broadcasting Corporation). Seven years later the SMPTE (Society of Motion Picture and Television Engineers) study group on high-definition television was formed. HDTV had its first debut in 1981. At this time the technology was not ready to be marketed to consumers for many different reasons. There were no television broadcasters broadcasting in high-definition and the HD technology still needed work.

Today HDTV has finally made its way into millions of homes after 35 years of development.

Description


Televisions today are far more complex and complicated than in years past. In the past all you had to decide upon really was what size television you wanted, or what features it had, but today it has become a very difficult decision to make. Now there are so many sizes, shapes, differences in technical design, contrast differences, quality differences and many more factors to consider when purchasing a new television.

Gone are the days of just the CRT (cathode-ray tube) television. Today there are plasma televisions, LCD (liquid crystal display) televisions, and a variety of projection televisions, some using DLP (digital light processing) and others using LCoS (liquid crystal on silicon). Each type of television comes with its own set of pros and cons and weighing these becomes an important decision when it comes time to buy a new television. For example, Plasma televisions offer very high contrast ratios compared to LCDs. LCDs have a variety of contrast ratios ranging from smaller 500:1 to some of them having 7000:1 ratios. Most Plasma televisions on the other hand usually have a contrast ratio of 10000:1. Plasma televisions are far brighter and can display a darker black color then LCDs. Plasma televisions also have a wider angle of viewing than LCDs. When looking at an LCD from the corner of the television it becomes distorted and hard to see, but plasma has a better angle of viewing, but not quite as good as the old CRT which was relatively unaffected by angle of viewing.

Plasma televisions do have cons however. The brightness of the display tends to dim over the life cycle of the television. Also, in the early stages of the life cycle the plasma television has a chance of burn-in. Television broadcasts that use consistent overlays (i.e. score overlay during a football game) or video games that display the same image in the exact same place can occasionally cause burn-in. Plasma televisions can also cause what is called a Rainbow Effect. Although the Rainbow effect is more often seen with DLP projection televisions, it can also happen with plasma televisions. LCDs have an advantage in that most offer the ability to act as both a television and as a monitor for your PC or Mac.LCDs also have no problems with burn-in, however, with LCD televisions you also have to worry about dead pixels. CRTs are still very common in most households and they do offer some advantages. They are cheaper and they do not have any Rainbow Effect, angle of viewing problems or dead pixels. However, they are simply just an old outdated technology that is slowly fading away. They tend to be far heavier than LCD televisions and plasma televisions, but even though old and outdated, some still find it hard to let go of the trusted CRT which has been around far longer than any other type of television.
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Images of three types of televisions. The left most image is a CRT television, an LCD television is in the middle, and a Plasma television is on the right.

Amongst all of these types to choose from, there are many other new factors to consider. The major factor comes down to the addition of high-definition. Standard definition CRT televisions run in the 480i format. This was the common format for many years in which cable television, video game consoles, and many other sources used to run on, and most still offer this format. Most homes today still only have standard 480i televisions. Some CRTs however are capable of producing high-definition resolutions, but today most high-definition sets are either LCD, Plasma, or projection. Now with high-definition on a major rise, most sources are offering higher resolution formats.

480i represents a resolution. It means that there are 480 lines being displayed on the television in an interlaced pattern. The new formats introduced with high-definition televisions are 720p, 1080i, and 1080p. Anything above and including 720p are technically considered to be running in "high-def".All high-definition resolutions run in the aspect ratio of 16:9, where the 16 describes the width of the television and the 9 represents the height. 16:9 is considered to be wide screen which allows a wider picture than 4:3 aspect ratio which most standard-definition televisions use.

Now there is also a 480p format which is considered EDTV (enhanced-definition television) but not high-definition. The lower case p stands for progressive scan, which is a different way of rendering the display. In the case of interlaced, each odd line is the first to be displayed and then the remaining lines are rendered to make the picture. With progressive scan, the lines are all displayed at once, thus rendering twice as fast as interlaced formats. Although 480p is not considered high-definition, it does differ itself from 480i in that its displays tend to be clearer and brighter. However, 480p also differs in that it needs component, DVI (digital visual interface) or HDMI (high-definition multimedia interface) cables for it be displayed, as 480i only requires standard composite video cables. The same applies for 720p, 1080i, or 1080p resolutions.

720p is the first resolution to be considered high-definition, and is the most commonly used. Running at a resolution of 1280x720 (480i runs at 640 x 480), 720p does not differ much from 480p except that it now renders 720 lines instead of 480. But this addition in lines makes a significant difference. It brings out a new level in picture that is brighter, clearer, and sharper than standard 480i. 1080i and 1080p both run a resolution of 1920x1080, with the one of differences being only one is interlaced and the other is progressive scan. 1080p is currently the best high-definition resolution possible, but most televisions that have it are relatively expensive and it is not as common as 720p or 1080i. Also, most sources do not output a signal in 1080p, so it is not yet being fully utilized. Most high-definition television broadcasts are being sent out in either 720p or 1080i. Blu-Ray players which come as stand alone units or included in the PlayStation 3 video game console and the HD-DVD drive add-on for the Xbox360 are only some of the sources that output in 1080p.

Application


For the average consumer, HDTVs can seem overwhelming, both in terms of price and complexity. HDTV's are not the easiest thing to go shopping for since there are so many types these days, and you may find yourself wondering why you should go to the trouble. The answer is depth. HDTV's bring an unmatched clarity to your home theater. Whether it is your favorite TV show, movie, or games, HDTV can help you enjoy it that much more.

Gaming technology has really taken off in the last few years. The PS3 with its new Blu-Ray technology hit the shelves late last year in 2006, and XBOX360 the year before. Both of these new gaming systems really can not be taken full advantage of without an HDTV. In fact most games now are being designed around that fact that soon everyone will have an HDTV.

If you have not heard about the epic battle between Blu-Ray and HD-DVD, you will soon. A year ago, Blu-Ray offered superior storage space at a higher price. Recently however, HD-DVD has released a newer disk that comes very close to the storage space offered by Blu-Ray but at a cheaper price. What this means for the consumer is cheaper and better home movie experiences.

TV stations have been gearing up for HDTV as well. While you can find a few channels today being broadcast in HD, the goal is to have all stations be required to broadcast in HD sometime in the next year or two. Some of the current stations that offer high-definition broadcasts are ABC, ESPN, CBS, NBC, FOX, The Discovery Channel, HBO, TNT, and there are more out there that do so, and plan to do so in the future.

Where is it going?


All technologies have a life cycle. They come into use, they grow to become a standard technology, they become outdated and then they die. HDTV is no different. This technology is still in the beginnings of its growth stage. Most people have not jumped on the HD bandwagon quite yet, but it is getting there. In 2005 about 20 million HDTVs were shipped out around the world, by 2010 this number is expected to reach 60 million. Thats a 300% growth rate in just 5 years. HD still has yet to really come into its own. Cost, technical concerns, and many people's lack of a desire to upgrade are currently still holding it back to a degree, however, as the figures show, that is slowly changing. It is easy to go so far as to say that HD is just getting started. With the new disk formats geared for it, the new game consoles built to support it, and the rise of HD channels, HDTV is just beginning to achieve its potential. In the future I think we can expect HD to become the norm rather than the exception as utility for the feature increases and cost decreases.

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Terminology


1080i - 1080i means that the resolution of the picture is 1920 vertical pixels by 1080 horizontal pixels and i stands for interlaced scanning. Interlaced scanning is based on the principle that the screen shows every odd line at one scan of the screen and then all the even lines in a second scan.

1080p - 1080p means that the resolution of the picture is 1,920 vertical pixels by 1,080 horizontal pixels and p stands again for progressive scanning. This format works on the same principle as 720p; the only difference is that in this type there are more pixels and the resolution is better.

16:9 - 16:9 is aspect ratio of movie screen and wide-screen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height.

4:3 - 4:3 is aspect ratio of traditional squarish National Television Systems Committee (NTSC) TV screens; it stands for four arbitrary units of width for every three arbitrary units of height.

720p - 720p means that the resolution of the picture is 1,280 vertical pixels by 720 horizontal pixels and p stands for progressive scanning. Progressive scanning offers a smoother picture as 720 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second.

Advanced Television Systems Committee (ATSC) - Advanced Television Systems Committee is responsible for establishing and developing digital television standards, as well as all 18 formats of Digital TV.

Aspect ratio - Aspect ratio is ratio of width to height of a TV screen. It may be either traditional squarish 4:3 ratio of the National Television Systems Committee (NTSC) TV screen or 16:9 ratio of wide-screen DTV formats for all HDTV (High Definition) and some SDTV (Standard Definition).

DLP - (Digital Light Processing) A data projection technology from TI that produces clear, readable images on screens in lit rooms. DLP is used in all ends of the projection spectrum, from data projectors that weigh only a few pounds to large rear-projection TVs to electronic cinema projectors for movie theaters.

Dolby Digital (Dolby AC-3) - Dolby Digital, also called Digital 5.1 or AC-3, is a five-channel surround sound system which delivers CD-quality digital audio and provides five channels of full frequency for front left, front right, center, surround left and surround right speakers, plus one channel for LFE (low frequency effect) sub-woofer. It is the official audio standard for Digital TV and HDTV.

DTV (Digital Television) - DTV stands for Digital Television. It refers to all digital television formats and standards established by the Advanced Television Systems Committee (ATSC). Two basic DTV standards are HDTV (high-definition television) and SDTV (standard-definition television)

EDTV (Enhanced-Definition Television) - EDTV stands for Enhanced Definition Television. The picture quality of EDTV is superior to that of standard analog TV (480i) but not as good as HDTV (1080i or 720p). EDTV displays the picture at a resolution of 852x480 (480p) lines in either 4:3 or 16:9 aspect ratios and it includes Dolby Digital sound system.

Flat-panel TV - Flat-panel TV typically displays picture using gas plasma or LCD technology and is only a few inches thick.

Front-projection TV - Front-projection TV comprises 2 parts – a separate front projector (usually placed on a table or ceiling-mounted) and a reflective screen (or simply a wall). The projector is placed at one end of the room, the screen is at the other end, and the speakers may be placed wherever they will provide you good sound experience. The picture can be rather large but remember – the larger the picture, the more visible the pixels or scan lines and the darker the image.

HDTV (High-Definition Television) - HDTV stands for High Definition Television. This highest-resolution subset of Digital Television offers film like picture quality with impressive surround sound. With twice the vertical and horizontal picture resolution, the picture of HDTV is approximately twice as sharp as that of NTSC. HDTV has wide-screen aspect ratio of 16:9 and Dolby Digital sound system. Currently used HDTV formats - 1080i and 720p both offer reduced motion artifacts like ghosting and dot crawl.

LCD (Liquid Crystal Display) - LCD stands for Liquid Crystal Displays. It refers to a flat panel technology which uses liquid crystals sandwiched between two glass plates for example in laptop computers, other small portable displays and also in televisions. Wide-screen HDTVs are available with displays of adequate resolution up to about 37 inches.

Picture-in-picture (PIP) - Picture-in-picture is a television feature in which you can see one program inside a small window on the screen, while watching another program on the large background screen. You can choose whatever you wish – you can watch two TV programs simultaneously or you can watch TV and video or DVD at the same time.

Pixel - Pixel comes from the words “picture element” and it refers to the smallest element in a television picture. Pixels are single displayable video dots from which the overall picture is made up.

Plasma Displays (PDP) - Plasma display is created by thousands of tiny tubes filled by ionized gas in a plasma state. Ionized gas is very light and flat panel TVs made by this technique can be even hanged on the wall! Plasma displays offer excellent resolution and color and they are the most suitable for the home theater.

Progressive Scanning - Progressive scanning is used by some HDTVs. Progressive scanning offers rather smooth picture as 720 or 1080 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second. Some displays, for example LCD and plasma use progressive scanning method, while CRTs may use progressive (e.g. in computer monitors) or interlaced scanning method.

Rear Projection - Rear projection is a TV system where the picture is projected against a mirror inside the cabinet and you can watch it as you would an average television. Until recently, the rear projection TVs comprised three CRTs but the new types of rear projection TVs include LCD.

Resolution - Resolution reflects the density of lines, and dots per line which make up a visual image. It is measured by the number of pixels displayed. The level of resolution directly affects picture quality. Usually the higher number of lines and dots means also sharper and more detailed picture. Analog TV has a little over 200,000 color pixels while HDTV, with 1080 vertical pixels and 1920 horizontal ones, has more than 2 million pixels creating the image.

Set-top Box (STB) - Set-top box is responsible for receiving, converting and sending the picture and sound of the broadcast to the associated television. If your HDTV-ready TV has no built-in HDTV tuner you must connect it to a compatible HDTV STB first. Until then it will not receive and display digital television programs.

Wide-screen - Wide-screen TV is the television with 16:9 aspect ratio. 16:9 is the aspect ratio of movie screen and wide-screen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height.

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