Useful Notes / High Definition
The same image at standard definition and high definition.

High Definition is basically increasing the resolution of digital TV broadcasts to show more detail compared to the 625 lines of PAL or 525 of NTSC. Older Than They Think: Analog broadcasts in HD go back to the 1950s, but did not take off until the 2000s. Furthermore, computer users with VGA monitors have effectively had HD since the 1990s.

These three resolutions are generally regarded as HD:

  • 720p (1280x720, progressive-scan)
  • 1080i (1920x1080, interlaced)
  • 1080p (1920x1080, progressive-scan)

Usually broadcasters tend to choose between 720p and 1080i depending on their type of programming; for instance ABC, Fox, ESPN and the A&E/Lifetime networks go with 720p to reduce image blur during fast motion in sporting events and films, and to address bandwidth concerns. 1080i broadcasters such as NBC, CBS, the Discovery networks and Food Network and HGTV go for image clarity. However in many cases the average consumer has no need to understand either format, as they all provide a great picture. 720p sets are cheaper than 1080i televisions, though as prices go down, 720p sets are becoming fewer and fewer. 1080p is mainly a media resolution utilized by camcorders, video games, streaming services like Netflix and Blu-ray as it is not currently possible to broadcast a 1080p signal over the air.

Despite the list below, basically everything new since 2009 on major networks and cable has been filmed in high definition television in North America, and when Fox de facto ended their Saturday morning infomercial block for new Edutainment Shows in most markets, it meant that all the major American and Canadian broadcast networks are now solely run in HD. The few shows that were behind the times, such as America's Next Top Model and Big Brother, had varying reasons, such as probable unease by Tyra Banks over the format, and in the case of Big Brother the high cost of refitting a show with multiple voyeuristic cameras with the HD variety, or have a budget so low they have to use old SD technology by default. ANTM finally at least pulled the trigger in March 2012, but most of their setup remains "enhanced definition widescreen", which is marketing code for "not really HD". Big Brother pulled the HD trigger in 2014, but not because of laziness; the complicated retrofitting of the entire show to run HD took three years to complete, and the producers wanted it all-HD or none at all. Let's Make a Deal was be the final network program to make the switch with the 2014 season start.

The turning point for most programs in Syndication becoming HD was the 2011-12 season (one show, Swift Justice with Jackie Glass actually downgraded to SD because of the loss of Nancy Grace and a new studio in that season, and was swiftly canceled). The only shows remaining in SD are the trifecta of NBCUniversal's trash talk shows (Jerry Springer, Steve Wilkos and Maury) and others of its ilk, along with most of the low-tier court shows, mainly because ITT Tech and sketchy lawyer ads airing on those shows don't really pay the HD upgrade bill well. Again in 2012-13 however, all of those programs upgraded to "enhanced definition widescreen", good enough to fill the screen at the very least, and are switching to HD cameras when the budget allows them to do so. The last true SD show in all of syndication, the morning business review First Business, ended in December 2014, but more because of local morning newscasts stealing their timeslots than any technological issues.

The ultimate resolution, which is drooled over by home theater buffs as it's the exact size of a 'frame' of a digital theatrical film, has a width of 4096 pixels and a varying height between 2200-3100 pixels depending on film aspect ratio standard; this is known as "4k". Note that "4k" is named after the approximate width in pixels, while 720 and 1080 are named after the height, hence, 4k is roughly twice as big in each dimension as 1080, not four times.

An increasing number of television programmes are now filmed in the format, though the majority of films are still filmed using celluloid. Movies that were shot on film have also been "high-deffed" from the original prints which technically are already HD (and nearly every film now is transferred to a digital format after editing via computer at a resolution slightly above or roughly twice that of 1080p). With the increasing availability of HD camcorders and the increasing popularity of the winning format in the brief HD-DVD war, Blu-ray, HD will become the norm. Consumer items such as the iPhone and Flip cams, and even $100 point-and-shoots with HD capability have accelerated this transition even further.

Some classic sitcoms and dramas which are on film can also be remastered into HD if the original negatives are available; this is seen on many shows which air on Universal HD and HD Net, along with programs such as the original Star Trek, which saw an acclaimed re-release in the format in both syndication and on Blu-ray.

The net result of this has been to show more detail and clarity on pretty much everything, from football replays to craggy faces, and also given both makeup artists and local news anchors who could get by with just a smidge of makeup much bigger challenges to deal with.

It's also resulted in a lot of people buying new televisions, especially in the United States after the FCC had forced the digital conversion (originally planned February 12th, 2009 but delayed by the President to June 12th).

Of The Sixth Generation of Console Video Games, the PlayStation 2 and Xbox both technically supported HD, but very few games used those modes, especially on the PS2, which only had TWO games that supported 1080i (Gran Turismo 4 and Tourist Trophy, which, it should be noted, ran on the same Game Engine). The HDTV Arcade Game Database highlights which games do support the 720p and 1080i modes. Homebrew for either platform will be more likely to leverage the higher resolution. Most games (but not all) among all four consoles support 480p, at the very least.

Of The Seventh Generation of Console Video Games (the PlayStation 3, Xbox 360, and Wii), only the Wii doesn't have HD capabilities. This has the side effect of making it so that some PS3 and 360 games have near illegible text or HUD elements on non-HD TVs (since the game programmers expected them to be played on widescreen HD sets), a problem not present in the Wii due to the aforementioned lack of HD, though the Wii's 480p resolution is considered enhanced definition. The Wii U, Xbox One and PlayStation 4 — in other words, all current home consoles — are in HD.

For the sake of clarity, the following are what [something] definition is defined as.

  • Standard Definition (SD): Depending on the format, it's either 480 (Systems M and N) or 576 (System B through K', except Systems E and F) horizontal lines interlacednote . The format can be widescreen or not. There is no width measurement as the width was considered to be limited by the allocated video bandwidth in the analog era, which can be anywhere between 6-8MHz.
  • Enhanced Definition (ED): The same as standard definition, but is progressive scan. In the digital era, it's equivalent would be roughly 640x480 (VGA) and 768x576 for 4:3 ratio transmissions, and 854x480 (FWVGA) and 1024x576 (WSVGA) for Widescreen transmissions.
  • High Definition (HD): 1280x720 progressive scan. Sometimes also retroactively applied to analog Systems E and F (819i) and Japan's Hi-Vision format (1035i).
  • Full High Definition (FHD): 1920x1080 interlaced or progressive scan.
  • Quad High Definition: 2560x1440, usually used on computers and is 4 times the resolution of 720p
  • Ultra High Definition (UHD) or 4K: Defined as 3840x2160 on The Other Wiki, and is basically 4 times the resolution of 1080p.
  • Full Ultra High Definition (FUHD) or 8K: Definied as 7680x4320, or 16 times the resolution of 1080p.

The terminology in the market seems to have shifted from how many vertical lines there are (e.g., 720 or 1080) to the approximate horizontal resolution (e.g., 4K and 8K). Note that for digital cinema, 4K and 8K are actually over 4000 and 8000 pixels respectively.
The Other Wiki has a much more comprehensive list for your liking. Here are just a few examples.

Programmes shot in High Definition:

Films shot on High Definition Video: