A method of squeezing the left and right sides of a widescreen image to fill the screen. If you viewed an anamorphic image in its raw form on a 4:3 screen, it will appear vertically stretched, but when outputted in its intended widescreen format, will display in its intended format. DVDs that store a movie using anamorphic techniques will use a stored 'stretched' 4:3 image, which will then be 'unstretched' when played back on a widescreen 16:9 display.
This refers to the height and width of an image. The standard widescreen format used in HDTV is 16:9, while ordinary televisions and computer monitors use 4:3. Cinema aspect ratios can go up to 2.39:1.
Raw digital video footage requires a very large amount of storage and bandwidth. To get around this, video is compressed in a way that reduces the size of individual frames (similar to JPEG, GIF and other image compression types). In addition, the differences between frames can be recorded, rather than the individual frames themselves. For example, a sequence showing a plane flying against a blue background would result in only information about the position of the plane being noted. Different compression types can alter the quality and are often (but not always) the resulting trade off between maintaining quality and reducing file size.
Despite being the most common type of TV or monitor, cathode ray tube units will likely phase out quickly among HDTV LCDs, plasmas, rear-projection and projectors. CRTs still hold one advantage, however, where they can maintain a good quality image regardless of resolution. LCD panels must convert a signal into the screen's native resolution, which can have varying effects on image quality.
Digital Light Processing is a technology used in projectors and projection televisions. Images are created by light that is reflected off thousands of tiny mirrors -- one mirror for each pixel -- sitting on top of a Digital Micromirror Device (DMD). In single DLP units, a spinning colour wheel sits between the mirrors and the light source to create the RGB image. Triple DLP models use individual DMDs for each colour.
Digital TV is a broad label given to any television broadcast carried in digital form. This allows for multiple channels, data transmission, and high definition TV. Its digital mode also frees it from common analogue reception problems like ghosting, but also makes it susceptible to compression artifacts found in other compressed video signals. Additionally, unlike analogue signals that get weaker at the fringes of reception, digital broadcasts are either on or off. That is, you'll receive a clearer image than analogue, but if the signal weakens you won't receive anything at all. That said, the advantages of DTV are far more significant than analogue, and Australian broadcasters are currently mandated to switch to DTV by 2008.
High definition TV (or video) commonly refers to digital video modes higher than SDTV, and typically falls under the 720p and 1080i types. The two modes are referred to according to the horizontal lines in the video signal, as well as the mode with which the frames are drawn on the screen. In these instances, 720p refers to a 16:9 widescreen signal with a resolution of 1280 x 720, with each frame displayed individually (or progressively) on the screen. 1080i refers to the same 16:9 aspect ratio, but is displayed at 1920 x 1080 resolution using an interlaced method (odd and even lines are alternately displayed very quickly). The highest HDTV mode is 1080p, however there are few screens that can achieve this. When purchasing a HDTV, ignore claims that a unit is 'HD-ready', 'HD enhanced' or 'HD compatible'. Sometimes, these screens simply receive the HDTV signal and downscale it to fit onto the screen. Always look for the native resolution to find if you truly have a TV capable of displaying the full signal.
LCD TVs are falling in price and increasing in size every year. Like LCD monitors, they have a fixed or native resolution, which represents the ideal resolution to display the picture on the screen. LCDs consume less space and energy than CRTs, but on average offer a lower contrast ratio compared to CRTs and plasmas. Like LCD monitors, they can also suffer from dead pixels. LCD technology is also found in projectors and rear projection televisions.
Plasma screens have been around for decades, and prior to LCD TVs, were the defacto luxury thin panel display. Plasma screens can be produced in very large sizes, are bright, and have a relatively high contrast ratio. The flipside is they can suffer from dead pixels and 'burn in', the latter being a left over visual artifact from a static image on the screen, like a TV channel's logo in the bottom corner.
Rear projection TV
RPTVs are mostly HDTV compatible. They work by using a built-in projector to display the image on the rear of the screen. Traditionally, RPTVs were bulky and poor quality, however recent advancements have seen the size decrease significantly, with better image quality. LCD and DLP projectors have largely replaced the old CRT projectors, which have contributed significantly to the improvements. As with ordinary projectors, lamp life is a serious consideration and you may need to fork out several hundreds of dollars periodically to keep it running.