HDTV defined

Welcome to this weekend's high-def feature: a listing of those somewhat confusing, but oh-so-necessary HD terms. Sure, you could look 'em all up on the awesome Wikipedia, but we wanted one place to corral them for you. It's not the "end-all, be-all" list by any means, but we hope it helps you begin to better understand our HDTV world. I've put these basic definitions together from my own knowledge, however, where I have pulled information from another source, I have provided a link.

Don't hesitate to use our contact form if you have additional terms you want to see when we update the list. Thanks goes out to the readers that used our contact form this week and sent suggested terms in. Ok, 'nuff said: on to the list!

480p: Four-eighty-p is an EDTV resolution. It means that there are 480 horizontal display lines and they are shown in a progressive format. 480p is not an HDTV format.

720p: Seven-twenty-p is an HDTV resolution. It means that there are 720 horizontal display lines and they are shown in a progressive format. This is the format currently used by ABC, Fox and ESPN-HD.

1080i: Ten-eighty-i is an HDTV resolution. It means that there are 1,080 horizontal lines of resolution and they are shown in an interlaced format. This is the format currently used by CBS, NBC, UPN, WB, HDNet, Discovery-HD, TNT-HD, Showtime-HD, and HBO-HD.

1080p: Ten-eighty-p is an HDTV resolution. Like 1080i, there are 1,080 horizontal lines of resolution, but they are show in a progressive format. There currently is no 1080p programming, however a 1080p set will likely look better than a 1080i set (all things being equal) for faster motion and smoother video.

Aspect ratio: A ratio of an image width to it's height. 16:9 is a widescreen aspect as the ration is 1.78:1. 4:3 is a typical full frame aspect on older televisions and is 1.33:1.

ATSC: Advanced Television System Committee, or the DTV system used today. ATSC currently uses MPEG-2 compression for the signal and can take up to 19.39 Megabits-per-second of bandwidth. An ATSC tuner is a digital tuner.

Brightness: A measurement of the light output that can be displayed. The lower the brightness, the more that ambient room light will interfere with a display. Measured in nits.

Color gamut:measure of the ability of the screen to reproduce a balanced and wide range of colors, is becoming important. In the CRT era, things were simple: CRTs displayed 72% of the full National Television System Committee (NTSC) television color gamut.

Component Video: An analog cable interface that is capable of transmitting digital HDTV signal. The video signal is sent in three pieces: one cable is used for luminance while the other two are used for color. This is the lowest quality interface for an HDTV signal.

Contrast: Usually indicated as a ratio, such as 1,000:1. This example would indicate that the brightest level of a set is 1,000 times brighter than the darkest level simultaneously. The greater the contrast ratio, the greater the difference in a set's ability to display light and dark levels

CRT: Cathode Ray Tube, the standard television display technology since the 1950's. An electron gun shoots electrons at a phosphor-coated screen. Red, green and blue phosphors determine the color output. Until recently, CRTs were known for the best color reproduction, brightness, contrast and resolution. In the past few years, flat-panel and micro-displays have closed the gap. CRTs have have had up to 1080i resolutions for several years.

DLP:Digital Light Processing, an HDTV display technology created by Texas Instruments. A DLP chip has thousands of small mirrors on hinges; one for each pixel of the display. The mirrors send light through color wheel to display the proper pixel color. Until recently, DLP chips were capable of 720p, but are now available for 1080p displays.

D-ILA: Direct-drive Image Light Amplifier, an HDTV display technology created by JVC. D-ILA is comprised of three chips and is a variant of LCoS. A light source is polarized by a Polarized Beam Splitter and reflects off of each of the chips. The image reflection is then focused through a lens, where it is magnified and projected onto the display. D-ILA sets are now available in 1080p displays.

DTV: Digital Television. There are 18 approved standards for DTV. SDTV, EDTV and HDTV are all subsets of DTV. This is television over a digital signal as opposed to an analog signal. Just because a signal is a DTV signal, that doesn't mean it is HDTV; the resolution determines if a DTV signal is SDTV, EDTV or HDTV.

DVI:

Digital Visual Interface is a cable interface similar to HDMI. The main difference is that DVI is for video only, while HDMI is video and audio. It is an all digital interface and provides a digital display signal comparable to HDMI. There are some DVI cables capable of HDCP support.

EDTV: Extended Definition Television. A subset of DTV and the middle resolution standard. It's better than SDTV, but not as good as HDTV. An EDTV signal is 480p (or 480-progressive). This is often called "DVD Quality" as it is the same display resolution as a DVD.

Frames per second (FPS): How many times per second that the display frame is created. The higher the FPS, the smoother the image will appear to the eye. Depending on the format, the FPS can vary from 24 to 60.

HDCP: High-bandwidth Digital Content Protection is an Intel-designed copyright specification supported by DVI and HDMI interfaces.

HDMI: High-Definition Multi-media Interface is a cabling medium between two high-definition components. HDMI is an all-digital interface that supports HDCP copyright protection. Currently, HDMI is the best interface for displaying a high-definition source on an HDTV.

HDTV: High Definition Television. Not the same as DTV; it's actually a subset of DTV. The HDTV standard requires a screen resolution of 720p or better.

Interlaced (that little"i" after a number, typically): Like Progressive, this indicates how the display is drawn. Interlaced means that half of the screen is drawn during a refresh; the other half is drawn on the next refresh. Example: first the odd lines are displayed, then the even lines. This happens so quickly that the eye sees the whole screen, however, during fast motion video, there could be some flicker or artifacting.

LCD: Liquid Crystal Display, and HDTV display technology. Used for years in computer monitors, LCDs are the prevalent flat-panel set in the 42-inch and under size. LCDs typically use a light source and color filters to create an image.

LCoS: Liquid Crystal on Silicon, an HDTV display technology. Similar to DLP, but uses liquid crystals as opposed to micro-mirrors. Liquid crystals are applied directly to the surface of a silicon chip coated with an aluminized layer making it highly reflective.

MPEG-2: Moving Pictures Expert Group or a standard compression technique. MPEG-2 us used for terrestrial DTV transmission, but will be going away in favor MPEG-4 compression in the near future.

MPEG-4: Moving Pictures Expert Group or a standard compression technique. MPEG-4, part 10 can compress audio and video more efficiently than the currently used MPEG-2.

Nit: A measurement of brightness. A nit is equal to one candela per square meter. The more nits, the greater the brightness. See candela.

NTSC: National Television System Committee or the analog television system widely utilized in the United States. Current DTV legislation calls for the NTSC system to shut down on April 7, 2009.

PDP: Plasma Display Panel, or plasma, is an HDTV display technology. PDPs are the prevalent flat-panel set in the over 42-inch size market. PDPs use plasma gases near the surface of the display and each pixel has three cells (Red, Blue, Green). As the pixels are electrically charged, the plasma gas is charged and emits light, while the phosphors determine the pixel color.

Progressive (that little "p" after a number, typically): A display format that indicates how the display is drawn. Progressive means that the entire display is drawn during every screen refresh. It generally shows a more fluid picture, especially with fast motion video. A display is either drawn via Progressive or Interlaced.

Projector: A projection unit, typically DLP or LCD, that projects an image on a wall or screen. Projectors are much smaller than standard display units and can create various screen sizes depending on distance from the screen. Until recently most HDTV projectors were 720p capable; 1080p units are now available.

Rear-Projection: DLP, LCoS and some LCDs are rear-projection displays that use a light source and some reflective technology to create the display.

SDTV: Standard Definition Television. A subset of DTV and the lowest resolution available at 480i (or 480-interlaced).

SED: Surface-conduction Electron-emitter Display, an HDTV display technology. SED applies the CRT electron-gun concept to a flat-panel footprint. Instead of one electron gun for all pixels, SED has electron-emitters for each individual pixel resulting in CRT quality in a flat-panel size. The first SED televisions are expected in late 2006.

Sharpness: The ability to resolve displayed edges. Reducing the sharpness on a set causes images to gain a fuzzy appearance. Increasing the sharpness can cause images to gain jagged edge appearances.

SXRD: Silicon X-tal Reflective Display, an HDTV display technology. This is Sony's version of LCoS and is capable of 1080p displays.