» High Definition TV (HDTV) Defined

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Editor's HDTV Pick

HP 47 inch MediaSmart 1080p LCD HDTV "Out of the box" digital media platform. Enjoy videos, pictures and music from home network + digital media delivered over your broadband Internet connection + 3 x HDMI

Advantages of HDTV

• HD is digital, so the signal will either provide an excellent picture, a picture with noticeable pixilation, a series of still pictures, or no picture at all
• Most HD programming and films are 16×9 semi-widescreen format
• Colors generally look more realistic
• Visual information is about 2-5 times more detailed overall
• Increased clarity and detail better suit larger screen sizes
• Dolby Digital 5.1 sound is broadcast along with standard HDTV video signals allowing full surround sound capabilities.

High-Definition television (HDTV)

• has a higher resolution than the traditional formats such as NTSC, SECAM and PAL
• generally defined as 1080 active lines at a 16 : 9 aspect ratio however, in some countries any resolution with 720 or more active lines is considered HDTV
• is broadcast digitally
• has at least twice the resolution of Standard Definition TV (SDTV)
• is capable of “theater-quality” audio because it uses the Dolby Digital (AC-3) format to support “5.1″ surround sound

Definitions and Notation

Progressive: an image is scanned and displayed following a path similar reading a page of text: line by line, from top to bottom.

Interlaced: an interlaced scan pattern in a CRT (cathode ray tube) includes only every second line followed by an alternating scan of the gaps between the lines of the previous scan. The afterglow of phosphor of CRT tubes combined with the human eyes persistence of vision results in two fields being perceived as a continuous image.

Field: A scan of every second line is called a field.

Display format notation:

(number of lines in display resolution)(p for progressive frames or i for interlaced fields)(number of fields per second)

eg. 1080p50 is 1920 x 1089 pixels of progressive encoding at 50 fields per second

Most commonly the frame rate is left out and can be assumed to be either 50 or 60. The example above would be expressed as 1080p.

Most HDTV systems support some standard resolutions and frame or field rates. The most common are noted below.

Standard Resolutions

• DV NTSC/VGA 720 x 480
• PAL 768 x 576
• XGA 1024 x 768
• HDTV 1280 x 720p
• Full HDTV 1920 x 1080p

Standard frame or field rates

• 24p (cinematic film)
• 25p
• 30p
• 50p
• 60p
• 50i (PAL/SECAM)
• 60i (NTSC)

For more in depth detail see the Wikipedia entry on HDTV upon which this post is based.