High-definition television
Overview
 
High-definition television (HDTV) is video that has resolution
Image resolution
Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....

 substantially higher than that of traditional television systems (standard-definition television
Standard-definition television
Sorete-definition television is a television system that uses a resolution that is not considered to be either enhanced-definition television or high-definition television . The term is usually used in reference to digital television, in particular when broadcasting at the same resolution as...

). HDTV has one or two million pixels per frame, roughly five times that of SD (1280 x 720 = 921,600 for 720p, or 1920 x 1080 = 2,073,600 for 1080p). Early HDTV broadcasting used analog techniques, but today HDTV is digitally
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...

 broadcast
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

 using video compression.
On 2 November 1936 the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 began transmitting the world's first public regular high-definition service from the Victorian Alexandra Palace
Alexandra Palace
Alexandra Palace is a building in North London, England. It stands in Alexandra Park, in an area between Hornsey, Muswell Hill and Wood Green...

 in north London.
Encyclopedia
High-definition television (HDTV) is video that has resolution
Image resolution
Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....

 substantially higher than that of traditional television systems (standard-definition television
Standard-definition television
Sorete-definition television is a television system that uses a resolution that is not considered to be either enhanced-definition television or high-definition television . The term is usually used in reference to digital television, in particular when broadcasting at the same resolution as...

). HDTV has one or two million pixels per frame, roughly five times that of SD (1280 x 720 = 921,600 for 720p, or 1920 x 1080 = 2,073,600 for 1080p). Early HDTV broadcasting used analog techniques, but today HDTV is digitally
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...

 broadcast
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

 using video compression.

History of high-definition television

On 2 November 1936 the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 began transmitting the world's first public regular high-definition service from the Victorian Alexandra Palace
Alexandra Palace
Alexandra Palace is a building in North London, England. It stands in Alexandra Park, in an area between Hornsey, Muswell Hill and Wood Green...

 in north London. It therefore claims to be the birthplace of television broadcasting as we know it today.

The term high definition once described a series of television systems originating from the late 1930s; however, these systems were only high definition when compared to earlier systems that were based on mechanical systems as few as 30 lines of resolution.

The British high-definition TV service started trials in August 1936 and a regular service in November 1936 using both the (mechanical) Baird 240 line and (electronic) Marconi-EMI 405 line (377i) systems. The Baird system was discontinued in February 1937. In 1938 France followed with their own 441-line system, variants of which were also used by a number of other countries. The US NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

 system joined in 1941. In 1949 France introduced an even higher-resolution standard at 819 lines (768i), a system that would be high definition even by today's standards, but it was monochrome only. All of these systems used interlacing and a 4:3 aspect ratio
Aspect ratio (image)
The aspect ratio of an image is the ratio of the width of the image to its height, expressed as two numbers separated by a colon. That is, for an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this...

 except the 240-line system which was progressive (actually described at the time by the technically correct term "sequential") and the 405-line system which started as 5:4 and later changed to 4:3. The 405-line system adopted the (at that time) revolutionary idea of interlaced scanning to overcome the flicker problem of the 240-line with its 25 Hz frame rate. The 240-line system could have doubled its frame rate but this would have meant that the transmitted signal would have doubled in bandwidth, an unacceptable option.

Colour broadcasts started at similarly higher resolutions, first with the US NTSC color system in 1953, which was compatible with the earlier B&W systems and therefore had the same 525 lines (480i) of resolution. European standards did not follow until the 1960s, when the PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

 and SECAM
SECAM
SECAM, also written SÉCAM , is an analog color television system first used in France....

 colour systems were added to the monochrome 625 line (576i) broadcasts.

Since the formal adoption of digital video broadcasting's (DVB) widescreen HDTV transmission modes in the early 2000s the 525-line NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

 (and PAL-M) systems as well as the European 625-line PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

 and SECAM
SECAM
SECAM, also written SÉCAM , is an analog color television system first used in France....

 systems are now regarded as standard definition television systems. In Australia, the 625-line digital progressive system (with 576 active lines) is officially recognized as high-definition.

Analog systems

In 1949, France started its transmissions with an 819 lines system (768i). It was monochrome only, it was used only on VHF for the first French TV channel, and it was discontinued in 1985.

In 1958, the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 developed Тransformator, the first high-resolution (definition) television system capable of producing an image composed of 1,125 lines of resolution aimed at providing teleconferencing for military command. It was a research project and the system was never deployed in the military or broadcasting.

In 1979, the Japanese state broadcaster Heirayuki MAedaNHK first developed consumer high-definition television with a 5:3 display aspect ratio. The system, known as Hi-Vision or MUSE after its Multiple sub-Nyquist sampling encoding for encoding the signal, required about twice the bandwidth of the existing NTSC system but provided about four times the resolution (1080i/1125 lines). Satellite test broadcasts started in 1989, with regular testing starting in 1991 and regular broadcasting of BS-9ch commenced on 25 November 1994, which featured commercial and NHK programming.

In 1981, the MUSE system was demonstrated for the first time in the United States, using the same 5:3 aspect ratio as the Japanese system. Upon visiting a demonstration of MUSE in Washington, US President Ronald Reagan
Ronald Reagan
Ronald Wilson Reagan was the 40th President of the United States , the 33rd Governor of California and, prior to that, a radio, film and television actor....

 was most impressed and officially declared it "a matter of national interest" to introduce HDTV to the USA.

Several systems were proposed as the new standard for the US, including the Japanese MUSE system, but all were rejected by the FCC because of their higher bandwidth requirements. At this time, the number of television channels was growing rapidly and bandwidth was already a problem. A new standard had to be more efficient, needing less bandwidth for HDTV than the existing NTSC.

Demise of analog HD systems

The limited standardization of analogue HDTV in the 1990s did not lead to global HDTV adoption as technical and economic reasons at the time did not permit HDTV to use bandwidths greater than normal television.

Early HDTV commercial experiments such as NHK's MUSE required over four times the bandwidth of a standard-definition broadcast—and HD-MAC was not much better. Despite efforts made to reduce analog HDTV to about 2× the bandwidth of SDTV these television formats were still distributable only by satellite.

In addition, recording and reproducing an HDTV signal was a significant technical challenge in the early years of HDTV (Sony HDVS
Sony HDVS
Sony HDVS was a range of high-definition video equipment developed in the 1980s to support an early analog high-definition television system thought to be the broadcast television systems that would be in use today...

). Japan remained the only country with successful public broadcasting
Public broadcasting
Public broadcasting includes radio, television and other electronic media outlets whose primary mission is public service. Public broadcasters receive funding from diverse sources including license fees, individual contributions, public financing and commercial financing.Public broadcasting may be...

 analog HDTV, with seven broadcasters sharing a single channel.

Rise of digital compression

Since 1972, International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...

's radio telecommunications sector (ITU-R
ITU-R
The ITU Radiocommunication Sector is one of the three sectors of the International Telecommunication Union and is responsible for radio communication....

) has been working on creating a global recommendation for Analogue HDTV. These recommendations however did not fit in the broadcasting bands which could reach home users. The standardization of MPEG-1
MPEG-1
MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to 1.5 Mbit/s without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting possible.Today, MPEG-1 has become...

 in 1993 also led to the acceptance of recommendations ITU-R BT.709
Rec. 709
ITU-R Recommendation BT.709, more commonly known by the abbreviations Rec. 709 or BT.709, standardizes the format of high-definition television, having 16:9 aspect ratio. The first edition of the standard was approved in 1990....

. In anticipation of these standards the Digital Video Broadcasting (DVB) organisation was formed, an alliance of broadcasters, consumer electronics manufacturers and regulatory bodies. The DVB develops and agrees on specifications which are formally standardised by ETSI.

DVB created first the standard for DVB-S
DVB-S
DVB-S is an abbreviation for Digital Video Broadcasting — Satellite; it is the original Digital Video Broadcasting forward error coding and demodulation standard for satellite television and dates from 1994, in its first release, while development lasted from 1993 to 1997...

 digital satellite TV, DVB-C
DVB-C
DVB-C stands for Digital Video Broadcasting - Cable and it is the DVB European consortium standard for the broadcast transmission of digital television over cable...

 digital cable TV and DVB-T
DVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...

 digital terrestrial TV. These broadcasting systems can be used for both SDTV and HDTV. In the US the Grand Alliance proposed ATSC as the new standard for SDTV and HDTV. Both ATSC and DVB were based on the MPEG-2 standard. The DVB-S2
DVB-S2
Digital Video Broadcasting - Satellite - Second Generation is a digital television broadcast standard that has been designed as a successor for the popular DVB-S system. It was developed in 2003 by the , an international industry consortium, and ratified by ETSI in March 2005...

 standard is based on the newer and more efficient H.264/MPEG-4 AVC
H.264/MPEG-4 AVC
H.264/MPEG-4 Part 10 or AVC is a standard for video compression, and is currently one of the most commonly used formats for the recording, compression, and distribution of high definition video...

 compression standards. Common for all DVB standards is the use of highly efficient modulation techniques for further reducing bandwidth, and foremost for reducing receiver-hardware and antenna requirements.

In 1983, the International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...

's radio telecommunications sector (ITU-R
ITU-R
The ITU Radiocommunication Sector is one of the three sectors of the International Telecommunication Union and is responsible for radio communication....

) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. One of the thornier issues concerned a suitable frame/field refresh rate, the world already having split into two camps, 25/50 Hz and 30/60 Hz, related by reasons of picture stability to the frequency of their main electrical supplies.

The IWP11/6 working party considered many views and through the 1980s served to encourage development in a number of video digital processing areas, not least conversion between the two main frame/field rates using motion vector
Motion vector
In video compression, a motion vector is the key element in the motion estimation process. It is used to represent a macroblock in a picture based on the position of this macroblock in another picture, called the reference picture....

s, which led to further developments in other areas. While a comprehensive HDTV standard was not in the end established, agreement on the aspect ratio was achieved.

Initially the existing 5:3 aspect ratio had been the main candidate but, due to the influence of widescreen cinema, the aspect ratio 16:9
16:9
16:9 is an aspect ratio with a width of 16 units and height of 9. Since 2009, it has become the most common aspect ratio for sold televisions and computer monitors and is also the international standard format of HDTV, Full HD, non-HD digital television and analog widescreen television ...

 (1.78) eventually emerged as being a reasonable compromise between 5:3 (1.67) and the common 1.85 widescreen cinema format. (Bob Morris explained that the 16:9 ratio was chosen as being the geometric mean of 4:3, Academy ratio
Academy ratio
The Academy ratio of 1.375:1 is an aspect ratio of a frame of 35mm film when used with 4-perf pulldown. It was standardized by the Academy of Motion Picture Arts and Sciences as the standard film aspect ratio in 1932, although similar-sized ratios were used as early as 1928.The Academy ratio is...

, and 2.4:1, the widest cinema format in common use, in order to minimize wasted screen space when displaying content with a variety of aspect ratios.)

An aspect ratio of 16:9 was duly agreed at the first meeting of the IWP11/6 working party at the BBC's Research and Development establishment in Kingswood Warren. The resulting ITU-R Recommendation ITU-R BT.709-2 ("Rec. 709
Rec. 709
ITU-R Recommendation BT.709, more commonly known by the abbreviations Rec. 709 or BT.709, standardizes the format of high-definition television, having 16:9 aspect ratio. The first edition of the standard was approved in 1990....

") includes the 16:9 aspect ratio, a specified colorimetry
Colorimetry
Colorimetry is "the science and technology used to quantify and describe physically the human color perception."It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space...

, and the scan modes 1080i
1080i
1080i is the shorthand name for a high-definition television mode. The i means interlaced video; 1080i differs from 1080p, in which the p stands for progressive scan. The term 1080i assumes a widescreen aspect ratio of 16:9, implying a frame size of 1920×1080 pixels...

 (1,080 actively interlaced lines of resolution) and 1080p
1080p
1080p is the shorthand identification for a set of HDTV high-definition video modes that are characterized by 1080 horizontal lines of resolution and progressive scan, meaning the image is not interlaced as is the case with the 1080i display standard....

 (1,080 progressively scanned
Progressive scan
Progressive scanning is a way of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence...

 lines). The British Freeview HD trials used MBAFF, which contains both progressive and interlaced content in the same encoding.

It also includes the alternative 1440×1152 HDMAC scan format. (According to some reports, a mooted 750-line (720p) format (720 progressively scanned lines) was viewed by some at the ITU as an enhanced television format rather than a true HDTV format, and so was not included, although 1920×1080i and 1280×720p
720p
720p is the shorthand name for 1280x720, a category of High-definition television video modes having a resolution of 1080 or 720p and a progressive scan...

 systems for a range of frame and field rates were defined by several US SMPTE standards.)

Inaugural HDTV broadcast in the United States

HDTV technology was introduced in the United States in the 1990s by the Digital HDTV Grand Alliance
Grand Alliance (HDTV)
The Grand Alliance was a consortium created in 1993 at the behest of the Federal Communications Commission to develop the American digital television and HDTV specification, with the aim of pooling the best work from different companies...

, a group of television, electronic equipment, communications companies and the Massachusetts Institute of Technology. Field testing of HDTV at 199 sites in the United States was completed August 14, 1994. The first public HDTV broadcast in the United States occurred on July 23, 1996 when the Raleigh, North Carolina
Raleigh, North Carolina
Raleigh is the capital and the second largest city in the state of North Carolina as well as the seat of Wake County. Raleigh is known as the "City of Oaks" for its many oak trees. According to the U.S. Census Bureau, the city's 2010 population was 403,892, over an area of , making Raleigh...

 television station WRAL-HD began broadcasting from the existing tower of WRAL-TV
WRAL-TV
WRAL-TV, virtual channel 5 , is a television station in Raleigh, North Carolina. WRAL-TV has been the flagship station of Capitol Broadcasting Company since its inception, and is currently the CBS affiliate for the Raleigh/Durham/Chapel Hill/Fayetteville area, known collectively as the Triangle...

 south-east of Raleigh, winning a race to be first with the HD Model Station in Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, which began broadcasting July 31, 1996 with the callsign WHD-TV, based out of the facilities of NBC
NBC
The National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...

 owned and operated station WRC-TV
WRC-TV
WRC-TV, channel 4, is an owned and operated television station of the NBC television network, located in the American capital city of Washington, D.C...

. The American Advanced Television Systems Committee
Advanced Television Systems Committee
The Advanced Television Systems Committee is the group, established in 1982, that developed the eponymous ATSC Standards for digital television in the United States, also adopted by Canada, Mexico, South Korea, and recently Honduras and is being considered by other countries.-See also:*ATSC...

 (ATSC) HDTV system had its public launch on October 29, 1998, during the live coverage of astronaut John Glenn
John Glenn
John Herschel Glenn, Jr. is a former United States Marine Corps pilot, astronaut, and United States senator who was the first American to orbit the Earth and the third American in space. Glenn was a Marine Corps fighter pilot before joining NASA's Mercury program as a member of NASA's original...

's return mission to space on board the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 Discovery
Space Shuttle Discovery
Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011...

. The signal was transmitted coast-to-coast, and was seen by the public in science centers, and other public theaters specially equipped to receive and display the broadcast.

European HDTV broadcasts

Although HDTV broadcasts had been demonstrated in Europe since the early 1990s, the first regular broadcasts started on January 1, 2004 when the Belgian company Euro1080
Euro1080
Euro1080 was the first commercial broadcaster in Europe to air full-time HDTV content. It was founded by Gabriel Fehervari in 2004 and is owned by Alfacam....

 launched the HD1 channel with the traditional Vienna New Year's Concert
Vienna New Year's Concert
The New Year's Concert of the Vienna Philharmonic is a concert of classical music that takes place each year in the morning of January 1 in Vienna, Austria...

. Test transmissions had been active since the IBC exhibition in September 2003, but the New Year's Day broadcast marked the official start of the HD1 channel, and the start of HDTV in Europe.

Euro1080, a division of the Belgian TV services company Alfacam, broadcast HDTV channels to break the pan-European stalemate of "no HD broadcasts mean no HD TVs bought means no HD broadcasts ..." and kick-start HDTV interest in Europe. The HD1 channel was initially free-to-air and mainly comprised sporting, dramatic, musical and other cultural events broadcast with a multi-lingual soundtrack on a rolling schedule of 4 or 5 hours per day.

These first European HDTV broadcasts used the 1080i format with MPEG-2 compression on a DVB-S signal from SES Astra
SES Astra
Astra is the name for the geostationary communication satellites, both individually and as a group, which are owned and operated by SES S.A., a global satellite operator based in Betzdorf, in eastern Luxembourg. The name is sometimes also used to describe the channels broadcasting from these...

's 1H satellite. Euro1080 transmissions later changed to MPEG-4/AVC compression on a DVB-S2 signal in line with subsequent broadcast channels in Europe.

The number of European HD channels and viewers has risen steadily since the first HDTV broadcasts, with SES Astra
SES Astra
Astra is the name for the geostationary communication satellites, both individually and as a group, which are owned and operated by SES S.A., a global satellite operator based in Betzdorf, in eastern Luxembourg. The name is sometimes also used to describe the channels broadcasting from these...

's annual Satellite Monitor market survey for 2010 reporting more than 200 commercial channels broadcasting in HD from Astra satellites, 185 million HD-Ready TVs sold in Europe (£60 million in 2010 alone), and 20 million households (27% of all European digital satellite TV homes) watching HD satellite broadcasts (16 million via Astra satellites).

In December 2009 the United Kingdom became the first European country to deploy high definition content on digital terrestrial television (branded as Freeview) using the new DVB-T2
DVB-T2
DVB-T2 is an abbreviation for Digital Video Broadcasting – Second Generation Terrestrial; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of digital terrestrial television....

 transmission standard as specified in the Digital TV Group
Digital TV Group
The Digital TV Group is the industry association for Digital Television in the United Kingdom : The Group was formed in 1995 to set technical standards for the implementation of digital terrestrial television in the UK and now encompasses all digital TV platforms and convergence issues...

 (DTG) D-book
D-book
The D-Book is the UK technical specification for Digital terrestrial television .The Digital TV Group has published and maintained the D-Book for over a decade and the specification is updated annually to keep up with the pace of development in UK DTT...

. The Freeview HD service currently contains 4 HD channels and is now rolling out region by region across the UK in accordance with the digital switchover process. Some transmitters such as the Crystal Palace transmitter are broadcasting the Freeview HD service ahead of the digital switchover by means of a temporary, low-power pre-DSO multiplex.

Notation

HDTV broadcast systems are identified with three major parameters:
  • Frame size in pixels is defined as number of horizontal pixels × number of vertical pixels, for example 1280 × 720 or 1920 × 1080. Often the number of horizontal pixels is implied from context and is omitted, as in the case of 720p and 1080p.
  • Scanning system is identified with the letter p for progressive scan
    Progressive scan
    Progressive scanning is a way of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence...

    ning or i for interlaced scanning.
  • Frame rate is identified as number of video frames per second. For interlaced systems an alternative form of specifying number of fields per second is often used.


If all three parameters are used, they are specified in the following form: [frame size][scanning system][frame or field rate] or [frame size]/[frame or field rate][scanning system]. Often, frame size or frame rate can be dropped if its value is implied from context. In this case the remaining numeric parameter is specified first, followed by the scanning system.

For example, 1920×1080p25 identifies progressive scanning format with 25 frames per second, each frame being 1,920 pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

s wide and 1,080 pixels high. The 1080i25 or 1080i50 notation identifies interlaced scanning format with 25 frames (50 fields) per second, each frame being 1,920 pixels wide and 1,080 pixels high. The 1080i30 or 1080i60 notation identifies interlaced scanning format with 30 frames (60 fields) per second, each frame being 1,920 pixels wide and 1,080 pixels high. The 720p60 notation identifies progressive scanning format with 60 frames per second, each frame being 720 pixels high; 1,280 pixels horizontally are implied.

50 Hz systems support three scanning rates: 25i, 25p and 50p. 60 Hz systems support a much wider set of frame rates: 23.976p, 24p, 29.97i/59.94i, 29.97p, 30p, 59.94p and 60p. In the days of standard definition television, the fractional rates were often rounded up to whole numbers, e.g. 23.976p was often called 24p, or 59.94i was often called 60i. 60 Hz high definition television supports both fractional and slightly different integer rates, therefore strict usage of notation is required to avoid ambiguity. Nevertheless, 29.97i/59.94i is almost universally called 60i, likewise 23.976p is called 24p.

For commercial naming of a product, the frame rate is often dropped and is implied from context (e.g., a 1080i television set). A frame rate can also be specified without a resolution. For example, 24p means 24 progressive scan frames per second, and 50i means 25 interlaced frames per second.

There is no standard for HDTV colour support. Until recently the color of each pixel was regulated by three 8-bit color values, each representing the level of red, blue, and green which defined a pixel colour. Together the 24 total bits defining colour yielded just under 17 million possible pixel colors. some manufacturers have produced systems that can employ 10 bits for each colour (30 bits total) which provides for a palette of 1 billion colors, saying that this provides a much richer picture, but there is no agreed way to specify that a piece of equipment supports this feature. Human vision can only discern approximately 1 million colours so an expanded colour palette is of questionable benefit to consumers.

Most HDTV systems support resolutions and frame rates defined either in the ATSC table 3, or in EBU specification. The most common are noted below.

High-definition display resolutions

Video format supported [image resolution] Native resolution [inherent resolution] (W×H) Pixels Aspect ratio (W:H) Description
Actual Advertised (Mpixel) Image
Aspect ratio (image)
The aspect ratio of an image is the ratio of the width of the image to its height, expressed as two numbers separated by a colon. That is, for an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this...

Pixel
Pixel aspect ratio
Pixel aspect ratio is a mathematical ratio that describes how the width of a pixel in a digital image compares to the height of that pixel....

720p
720p
720p is the shorthand name for 1280x720, a category of High-definition television video modes having a resolution of 1080 or 720p and a progressive scan...


1280×720
1024×768
XGA
786,432 0.8 4:3 4:3 Typically a PC resolution (XGA); also a native resolution on many entry-level plasma displays with non-square pixels.
1280×720
921,600 0.9 16:9 1:1 Standard HDTV resolution and a typical PC resolution (WXGA), frequently used by high-end video projectors; also used for 750-line video, as defined in SMPTE 296M, ATSC A/53, ITU-R BT.1543.
1366×768
WXGA
1,049,088 1.0 683:384
(approx. 16:9)
1:1 A typical PC resolution (WXGA); also used by many HD ready
HD ready
The HD ready is a certification program introduced in 2005 by EICTA , now DIGITALEUROPE....

 TV displays based on LCD
Liquid crystal display
A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

 technology.
1080p
1080p
1080p is the shorthand identification for a set of HDTV high-definition video modes that are characterized by 1080 horizontal lines of resolution and progressive scan, meaning the image is not interlaced as is the case with the 1080i display standard....

/1080i
1080i
1080i is the shorthand name for a high-definition television mode. The i means interlaced video; 1080i differs from 1080p, in which the p stands for progressive scan. The term 1080i assumes a widescreen aspect ratio of 16:9, implying a frame size of 1920×1080 pixels...


1920×1080
1920×1080
2,073,600 2.1 16:9 1:1 Standard HDTV resolution, used by Full HD and HD ready
HD ready
The HD ready is a certification program introduced in 2005 by EICTA , now DIGITALEUROPE....

 1080p TV displays such as high-end LCD
Liquid crystal display
A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

, Plasma and rear projection TVs, and a typical PC resolution (lower than WUXGA); also used for 1125-line video, as defined in SMPTE 274M, ATSC A/53, ITU-R BT.709;

Video format supported Screen resolution (W×H) Pixels Aspect ratio (W:H) Description
Actual Advertised (Mpixel) Image Pixel
720p
720p
720p is the shorthand name for 1280x720, a category of High-definition television video modes having a resolution of 1080 or 720p and a progressive scan...


1280×720
1248×702
Clean Aperture
876,096 0.9 16:9 1:1 Used for 750-line video with faster artifact/overscan compensation, as defined in SMPTE 296M.
1080p
1080p
1080p is the shorthand identification for a set of HDTV high-definition video modes that are characterized by 1080 horizontal lines of resolution and progressive scan, meaning the image is not interlaced as is the case with the 1080i display standard....


1920×1080
1888×1062
Clean aperture
2,005,056 2.0 16:9 1:1 Used for 1125-line video with faster artifact/overscan compensation, as defined in SMPTE 274M.
1080i
1080i
1080i is the shorthand name for a high-definition television mode. The i means interlaced video; 1080i differs from 1080p, in which the p stands for progressive scan. The term 1080i assumes a widescreen aspect ratio of 16:9, implying a frame size of 1920×1080 pixels...


1920×1080
1440×1080
HDCAM
HDCAM
HDCAM, introduced in 1997, is an High-definition video digital recording videocassette version of Digital Betacam, using an 8-bit DCT compressed 3:1:1 recording, in 1080i-compatible downsampled resolution of 1440×1080, and adding 24p and 23.976 PsF modes to later models...

/HDV
HDV
HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon and Sharp...

1,555,200 1.6 16:9 4:3 Used for anamorphic 1125-line video in the HDCAM and HDV formats introduced by Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

 and defined (also as a luminance subsampling matrix) in SMPTE D11
SMPTE D11
SMPTE 367M, also known as SMPTE D-11 and HDCAM, is a standard for the compression of high-definition digital video. D11 source picture rates can be 24, 24/1.001, 25 or 30/1.001 frames per second progressive scan, or 50 or 60/1.001 fields per second interlaced; compression yields output bit rates...

.

Standard frame or field rates

  • 23.976 Hz (film-looking frame rate compatible with NTSC
    NTSC
    NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

     clock speed standards)
  • 24 Hz (international film and ATSC
    ATSC
    ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....

     high-definition material)
  • 25 Hz (PAL
    PAL
    PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

    , SECAM
    SECAM
    SECAM, also written SÉCAM , is an analog color television system first used in France....

     film, standard-definition, and high-definition material)
  • 29.97 Hz (NTSC
    NTSC
    NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

     standard-definition material)
  • 50 Hz (PAL
    PAL
    PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

     & SECAM
    SECAM
    SECAM, also written SÉCAM , is an analog color television system first used in France....

     high-definition material)
  • 59.94 Hz (ATSC
    ATSC
    ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....

     high-definition material)
  • 60 Hz (ATSC
    ATSC
    ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....

     high-definition material)
  • 120 Hz (ATSC
    ATSC
    ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....

     high-definition material)


At a minimum, HDTV has twice the linear resolution of standard-definition television
Standard-definition television
Sorete-definition television is a television system that uses a resolution that is not considered to be either enhanced-definition television or high-definition television . The term is usually used in reference to digital television, in particular when broadcasting at the same resolution as...

 (SDTV), thus showing greater detail than either analog television or regular DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

. The technical standards for broadcasting HDTV also handle the 16:9 aspect ratio
Aspect ratio (image)
The aspect ratio of an image is the ratio of the width of the image to its height, expressed as two numbers separated by a colon. That is, for an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this...

 images without using letterbox
Letterbox
Letterboxing is the practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio. The resulting videographic image has mattes above and below it; these mattes are part of the image...

ing or anamorphic stretching, thus increasing the effective image resolution.

The optimum format for a broadcast depends upon the type of videographic recording medium used and the image's characteristics. The field and frame rate should match the source and the resolution. A very high resolution source may require more bandwidth than available in order to be transmitted without loss of fidelity. The lossy compression that is used in all digital HDTV storage and transmission systems will distort the received picture, when compared to the uncompressed source.

There is widespread confusion in the use of the terms PAL, SECAM and NTSC when referring to HD material. These terms apply only to standard definition television, not HD. The only technical reason for keeping 25 Hz as the HD frame rate in a former PAL country is to maintain compatibility between HD and standard definition television systems.

Types of media

Standard 35mm photographic film
Photographic film
Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...

 used for cinema projection has a much higher image resolution
Image resolution
Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....

 than HDTV systems, and is exposed and projected at a rate of 24 frames per second (frame/s). To be shown on standard television, in PAL-system countries, cinema film is scanned at the TV rate of 25 frame/s, causing a speedup of 4.1 percent, which is generally considered acceptable. In NTSC-system countries, the TV scan rate of 30 frame/s would cause a perceptible speedup if the same were attempted, and the necessary correction is performed by a technique called 3:2 Pulldown: Over each successive pair of film frames, one is held for three video fields (1/20 of a second) and the next is held for two video fields (1/30 of a second), giving a total time for the two frames of 1/12 of a second and thus achieving the correct average film frame rate.

Non-cinematic HDTV video recordings intended for broadcast are typically recorded either in 720p
720p
720p is the shorthand name for 1280x720, a category of High-definition television video modes having a resolution of 1080 or 720p and a progressive scan...

 or 1080i
1080i
1080i is the shorthand name for a high-definition television mode. The i means interlaced video; 1080i differs from 1080p, in which the p stands for progressive scan. The term 1080i assumes a widescreen aspect ratio of 16:9, implying a frame size of 1920×1080 pixels...

 format as determined by the broadcaster. 720p is commonly used for Internet distribution of high-definition video, because most computer monitors operate in progressive-scan mode. 720p also imposes less strenuous storage and decoding requirements compared to both 1080i and 1080p. 1080p-24 frame/s and 1080i-30 frame/s is most often used on Blu-ray Disc
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

; as of 2011, there is still no disc that can support full 1080p-60 frame/s.

Contemporary systems

Besides an HD-ready television set, other equipment may be needed to view HD television. In the US, cable-ready TV sets can display HD content without using an external box. They have a QAM tuner
QAM tuner
QAM stands for quadrature amplitude modulation, the format by which digital cable channels are encoded and transmitted via cable television providers...

 built-in and/or a card slot for inserting a CableCARD
CableCARD
CableCARD is a special-use PCMCIA card that allows consumers in the United States to view and record digital cable television channels on digital video recorders, personal computers and television sets without the use of other equipment such as a set top box provided by a cable television company...

.

High-definition image sources include terrestrial broadcast, direct broadcast satellite, digital cable, IPTV
IPTV
Internet Protocol television is a system through which television services are delivered using the Internet protocol suite over a packet-switched network such as the Internet, instead of being delivered through traditional terrestrial, satellite signal, and cable television formats.IPTV services...

, Blu-ray
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

 video disc (BD), and internet downloads. Sony's Playstation 3
PlayStation 3
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...

 has extensive HD compatibility because of the Blu-ray platform, so does Microsoft's Xbox 360
Xbox 360
The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...

 with the addition of Netflix streaming capabilities, and the Zune marketplace where users can rent or purchase digital HD content. The HD capabilities of the consoles has influenced some developers to port games from past consoles onto the PS3 and 360, often with remastered graphics.

Recording and compression

HDTV can be recorded to D-VHS
D-VHS
D-VHS is a digital recording format developed by JVC, in collaboration with Hitachi, Matsushita, and Philips. The "D" in D-VHS originally stood for Data VHS, but with the expansion of the format from standard definition to high definition capability, JVC renamed it Digital VHS and uses that...

 (Digital-VHS or Data-VHS), W-VHS
W-VHS
W-VHS is a HDTV analog recording videocassette format created by JVC. The format was originally introduced in 1994 for use with Japan's Hi-Vision, an early analog high-definition television system named MUSE....

 (analog only), to an HDTV-capable digital video recorder
Digital video recorder
A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...

 (for example DirecTV
DirecTV
DirecTV is an American direct broadcast satellite service provider and broadcaster based in El Segundo, California. Its satellite service, launched on June 17, 1994, transmits digital satellite television and audio to households in the United States, Latin America, and the Anglophone Caribbean. ...

's high-definition Digital video recorder
Digital video recorder
A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...

, Sky HD
Sky HD
Sky+ HD is the brand name of the HDTV service launched by BSkyB on 22 May 2006 in the United Kingdom and Ireland to enable high definition channels on Sky to be viewed. For the first 2 years after launch, the service was branded Sky HD. The service requires the user to have a Sky+ HD Digibox...

's set-top box, Dish Network
Dish Network
Dish Network Corporation is the second largest pay TV provider in the United States, providing direct broadcast satellite service—including satellite television, audio programming, and interactive television services—to 14.337 million commercial and residential customers in the United States. Dish...

's VIP 622 or VIP 722 high-definition Digital video recorder
Digital video recorder
A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...

 receivers, or TiVo
TiVo
TiVo is a digital video recorder developed and marketed by TiVo, Inc. and introduced in 1999. TiVo provides an on-screen guide of scheduled broadcast programming television programs, whose features include "Season Pass" schedules which record every new episode of a series, and "WishList"...

's Series 3 or HD recorders), or an HDTV-ready HTPC. Some cable boxes are capable of receiving or recording two or more broadcasts at a time in HDTV format, and HDTV programming, some free, some for a fee, can be played back with the cable company's on-demand feature.

The massive amount of data storage required to archive uncompressed streams meant that inexpensive uncompressed storage options were not available in the consumer market until recently. In 2008 the Hauppauge 1212 Personal Video Recorder was introduced. This device accepts HD content through component video inputs and stores the content in an uncompressed MPEG transport stream (.ts) file or Blu-ray format .m2ts
.m2ts
M2TS is a filename extension used for the Blu-ray Disc Audio-Video MPEG-2 Transport Stream container file format. It is used for multiplexing audio, video and other streams. It is based on the MPEG-2 transport stream container...

 file on the hard drive or DVD burner of a computer connected to the PVR through a USB 2.0 interface.

Realtime MPEG-2 compression of an uncompressed digital HDTV signal is prohibitively expensive for the consumer market at this time, but should become inexpensive within several years (although this is more relevant for consumer HD camcorders than recording HDTV). Analog tape recorders with bandwidth capable of recording analog HD signals such as W-VHS recorders are no longer produced for the consumer market and are both expensive and scarce in the secondary market.

In the United States, as part of the FCC's plug and play agreement, cable companies are required to provide customers who rent HD set-top boxes with a set-top box with "functional" Firewire (IEEE 1394) upon request. None of the direct broadcast satellite
Direct broadcast satellite
Direct broadcast satellite is a term used to refer to satellite television broadcasts intended for home reception.A designation broader than DBS would be direct-to-home signals, or DTH. This has initially distinguished the transmissions directly intended for home viewers from cable television...

 providers have offered this feature on any of their supported boxes, but some cable TV
Cable television
Cable television is a system of providing television programs to consumers via radio frequency signals transmitted to televisions through coaxial cables or digital light pulses through fixed optical fibers located on the subscriber's property, much like the over-the-air method used in traditional...

 companies have. , boxes are not included in the FCC mandate. This content is protected by encryption known as 5C. This encryption can prevent duplication of content or simply limit the number of copies permitted, thus effectively denying most if not all fair use
Fair use
Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders...

 of the content.

See also

  • 1HDTV
    1HDTV
    ZАО 1HDTV is a Russian TV company specialized in creating channels for satellite and cable transmission. The company was founded in 2007 in St. Petersburg. General Director is Nikolai Orlov....

  • Extreme High Definition
    Extreme High Definition
    Extreme High Definition, or XHD, is a term coined by Nvidia and Dell at the Consumer Electronics Show 2006 to emphasize gaming at resolutions higher than high definition. The term was created as a marketing term for Nvidia's Quad SLI setup and Dell's 3007WFP monitor.According to Nvidia, XHD is...

     (1440p) (4320p)
  • HDTV blur
    HDTV blur
    HDTV blur is a common term used to describe a number of different artifacts on modern consumer high-definition television sets.The following factors are generally the primary or secondary causes of HDTV blur; in some cases more than one of these factors may be in play at the studio or receiver end...

  • H.265
  • HD+
    HD+
    This article is about the television service "HD+"; for the computer screen resolution see Computer display standard.HD+ is a package of high definition digital satellite TV channels for German-speaking viewers and the company providing that package, based in Unterföhring near Munich, Germany...

  • List of digital television deployments by country
  • Ultra High Definition Television

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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