HDTVs: Glossary of terms
By The Vann’s Editorial Team
Last revised December 11th, 2009
120Hz panel response
Film is shot at 24 frames per second (fps), while television programming runs at 30 fps. Fitting 24 fps content onto a 30 fps screen isn’t a seamless process. A process known at 3:2 pulldown spreads out 24 frames into 30 by placing one frame on the screen three times and the next one after that two times, repeating the pattern. This can lead to stutter and artifacts. Some video content, like some special effects, is recorded at 60 fps which doesn’t work with the 3:2 pulldown. A TV with 120Hz image processing shows 120 frames per second (fps), allowing the TV to reproduce 24fps movies, 30fps television shows, and 60fps special effects programming without the stutter or artifacts from 3:2 pulldown. The reason this works is because 120 is evenly divisible by 24, 30, and 60. Instead of flashing a frame three times and the next two times, each frame will be flashed on the screen the same number of times. For example each movie frame will be placed on the screen five times. The end result is a smoother overall picture.
This is one form of high-definition TV. The number 720p signifies a pixel resolution of about 1280 horizontal pixels by 720 vertical pixels scanned progressively (lines scanned in sequence). Referring to the same resolution as 720p, 720i indicates interlaced scanning. (For a description of both progressive and interlaced scanning, see below.)
This is a second form of high-definition TV. The number 1080p signifies a pixel resolution of approximately 1920 horizontal pixels by 1080 vertical pixels scanned progressively (lines scanned in sequence). This is the highest definition currently available. Referring to the same resolution as 1080p, 1080i indicates interlaced scanning.
Anti-glare screen coating
Placing a plasma television near a light source can cause the picture on the screen to look dull or faded. An anti-glare coating applied to a screen will reduce glare from ambient light sources and help retain the brighter appearance of the picture.
Backlighting is a term most commonly used with LED LCDs. It refers to a TV with the light source used to show the picture placed behind the screen.
The expanded bandwidth of HDMI version 1.3 allows the use of a new format known as Deep Color which increases the maximum number of colors that can be displayed. In televisions, color is separated into Red, Green, and Blue groups (RGB). All other colors are formed by a combination of these three basic colors. Increasing the range of each of these color groups increases the total numbers of colors that can be displayed. So instead of the 16.7 million possible colors that can be displayed through previous versions of HDMI, version 1.3 and Deep Color can display up to 1.07 billion colors. The human eye can only detect about 16 million colors, but Deep Color can eliminate color banding artifacts while representing finer shades of gray by increasing the total number of displayable colors. (Deep Color provides for a wider spectrum of shades of gray as well). The result is a much smoother picture.
Digital Light Processing (DLP) technology uses a chip roughly the size of your palm to create an image. A light beam is shone from an incandescent lamp through a color wheel projecting red, green and blue colors onto the chip that contains up to 2 million microscopic, hinged mirrors. Each mirror is set at an independent angle to reflect the colors and form a pattern (or image). The resulting image is reflected onto a surface that magnifies and projects the image onto the TV screen.
Edge-lighting is another term used to describe LED LCDs. It refers to a TV where the picture's light bulbs are placed around the edge of the screen as opposed to behind the screen as in backlit models.
HDMI v1.3a with CEC
HDMI stands for High Definition Multimedia Interface. It is an all-digital interface that can transmit uncompressed audio and video content through a single cable. Video content can be standard, enhanced, or high definition, up to 1920 x 1080p. Up to eight channels of 192kHz audio can be transmitted. In practice, what this means is that the highest possible resolution video and the most advanced audio content can be transferred from the source to your home theater components via a single cable. It eliminates the mess of wires while providing high-resolution entertainment.
The original HDMI is called version 1.0. Version 1.3a is the newest upgrade with an increased bandwidth to handle even more information, including Deep Color. This allows the support of lossless compressed audio such as Dolby TrueHD and DTS-HD Master Audio, but it uses the same cable as version 1.0 and is still compatible with the older version.
CEC (Consumer Electronics Control) is a mandatory part of HDMI wiring. It is used for remote control functions and allows single-remote and even single-button control of CEC-enabled products. Products that are CEC-enabled are able to interface immediately. So if your receiver, DVD player and TV are all CEC-enabled, when you put a DVD into the player, the TV and receiver will automatically turn on and select the right audio and video modes.
The process of interlaced scanning divides the horizontal lines of pixels in a frame into a set of odd lines and a set of even lines. In 1/60th of a second, the odd lines will flash on the screen and in the next 1/60th of a second, the even lines will flash on the screen. In the space of 1/30th of a second, the entire frame has been shown on the screen in two separate flashes.
LCD flat panel
LCD is another kind of flat panel television. LCD (Liquid Crystal Display) is a TV display that applies an electrical charge to a layer of liquid crystals trapped between two pieces of polarized glass so light can shine through in a specific pattern. The pattern is displayed as an image on screen.
LED is one specific type of LCD TV. An “LED TV” is an LCD panel that uses LED bulbs for lighting the picture. There are two types of LED TVs, edge-lit and back-lit.
Plasma refers to one kind of flat panel television. With a plasma display, a mixture of gases is trapped between two pieces of glass and an electrical charge is applied to the gases. This causes certain elements in the mixture to light up. The light passes through the glass in a specific pattern. That pattern forms an image on the screen.
In progressive scanning, the lines of pixels are shown on the screen in succession. So the first line, followed by the second, the third, the fourth, and so on, are placed on the screen in order all within 1/30th of a second. This provides a smoother picture than interlaced scanning.
A general term for a TV display that reflects and magnifies an image onto the screen. Rear projection technology is housed in a deeper box than flat panels to allow space for reflection and magnification. Rear projection televisions may use CRT, LCD or DLP technologies to reproduce a video image. Also, while rear projection televisions tend to be larger than flat-panel televisions, they are, generally, still thinner than standard televisions.
Pictures on a television screen are a sum of tiny dots which are pieces of information called pixels. Resolution refers to the number of pixels on a television screen. The higher the resolution number, the more detailed the picture. Standard definition resolution is 480, while high definition resolution is 720 or 1080. Those numbers refer to the number of horizontal lines of pixels.
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