High Definition Television (HDTV) has become the new standard in home entertainment. It wasn’t that long ago that HDTV was a premium option when purchasing a television, but in recent years, that has changed. HDTV has become much more affordable and as such, is so commonplace that most televisions purchased today are High Definition Television sets.

photo credit: msk

In the past, one could expect to pay upwards of $3,000 for a High Definition Television. In recent years, however, the cost to buy an HDTV has come down significantly due to advances in consumer technology and increased consumer demand. Although many high-end HDTV models can run you into thousands of dollars, today you can purchase a High Definition Television for as little as $400 or $500.

What is High Definition Television?

HDTV is a video display that has significantly higher resolution than standard television. Typically, HDTV has millions of pixels per frame, which is many times that of its predecessor. This is accomplished by a number of means including digital video compression and advanced screen technologies.

A High Definition Television is measured by its screen resolution, identified by measures of their frame size, scanning system and frame rate. Most often, the resolutions are identified in shortened form, which tells the frame size and scanning system (1080p, for example).

Frame Size

The frame size is nothing more than a measure of the horizontal pixels and vertical pixels (1920×1080). Usually, only the vertical measure is used because the horizontal measure is implied by the aspect ratio (4:3, 16:9, etc.). In the previous example, the frame size has a 16:9 aspect ration, which is one of the most common. If an HDTV is said to have a 1080 pixel vertical resolution and a 16:9 aspect ratio, then the width would be 1920 pixels. As such, most manufacturers only note the vertical measurement since the horizontal measure can be extrapolated using the aspect ration.

Scanning System

There are two different scanning systems used, interlaced scanning and progressive scanning. The type of scanning used in an HDTV is identified by the letter “i” or “p” in the resolution (1080i is interlaced, 1080p is progressive). In a High Definition Television that uses interlaced scanning, half of the vertical lines are displayed in a rotating manner. Essentially, a 1080 resolution would display 540 lines at a time (all of the “odd” lines, then all of the “even” lines). This results in using half of the bandwidth, but also in a slightly less clear picture. With progressive scanning, all 1080 lines would be displayed at once, resulting in a clearer picture, but using twice the bandwidth.

Frame Rate

Frame rate is simply the number of frames displayed per second. HDTV frame rates typically range from 24 to 60 frames per second. The frame rate specification is usually dropped from the resolution that is identified by the manufacturer, but can be found in the TV’s specifications.

The most common High Definition Television resolutions are 720p, 1080i and 1080p. 1080p is probably the most common of these and is the resolution that is considered to be “true HDTV” or “full HDTV”.

Types of High Definition Television Displays

Plasma HDTV

Plasma displays use small cells that contain electrically charged ionizes gases and are common among HDTV sets in the 30″ and larger range. Plasma HDTV sets are known for producing deep blacks with a superior contrast ratio. Plasma displays typically have very wide viewing angles but are made from glass, so they can sometimes have a larger amount of glare than other display types. Many well known manufacturers such as Sony®, Philips®, and Vizio®, have discontinued using plasma displays.

LCD HDTV

LCD displays (or Liquid Crystal Displays) produce black and/or colored images by selectively filtering a white light. Millions of shutters combine to filter the light and display the appropriate image for each pixel. LCD displays offer very high resolution pictures at a more competitive price that plasma displays.

LED HDTV

LED displays use Light Emitting Diodes on a very small scale to produce a high resolution HDTV display. Most HDTVs with LED displays are actually not “true” LED displays, but LED-backlit displays. LED backlighting in an HDTV display results in a thinner panel, lower power consumption, a brighter display and better contrast levels.

High Definition Television has advanced significantly over recent years and will continue to do so as Manufacturers develop and improve the technology involved in HDTV.