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With the end to analog broadcasts looming in February 2009, I’d like to iterate some of the basic differences between conventional TV and high definition, or HDTV.

This article will convey the aspect ratios and resolutions for the following broadcast types:

• Standard definition
• Enhanced definition
• High definition (HDTV)
• Full, or True HDTV

In addition, I will touch on the various HDTV display options and their respective benefits, HDTV Built In v. HDTV Ready, and explain the concept of OTA (over-the-air) HDTV signals.

I am a HUGE proponent of HDTV.  That’s not to suggest that I watch a lot of TV, I simply enjoy and appreciate the technology, and the marked improvement in picture quality.  I have three HDTV’s in my house, including the one pictured at the beginning of this article (Samsung HL-S6767W Full HDTV), and one Standard TV, all connected to two satellite receivers, and I’ve owned at least one high definition display since 2004.

The difference owing to the extraordinary distinction in picture quality has everything to do with pixel count, which ultimately makes up a display’s resolution.  Following are the pixel counts for the above formats:

Standard def - 704 x 480 pixels (480i)
Enhanced def - 852 x 480 pixels (480p)
High def - 1,280 x 720p (progressive) or 1.920 x 1,080i (interlaced) pixels (720p or 1080i)
True High def - 1,920, x 1,080 pixels (1080p)

Standard Definition
Standard definition displays output their native signal in what is referred to as 480i, or 480-interlaced.  This means the image is presented as 480 interlaced horizontal lines from the top to the bottom of the screen.  The interlaced lines are displayed in an alternating fashion, such that 240 lines are scanned every 1/60th of a second on your display, yielding a full frame of Standard definition television in a 4:3 aspect ratio (non wide-screen).

Enhanced Definition
Enhanced definition, or DVD resolution, is the first of the three signals that is now digital as opposed to analog.  The difference in resolution between enhanced and standard definition is the digital version is referred to as 480p, not 480i.  The “p” stands for progressive, and simply means that the display will output 480 horizontal lines simultaneously, yielding a smoother picture at twice the resolution of standard definition.  Enhanced definition signals are typically in the wide-screen (16:9) aspect ratio.  This means if you are viewing an enhanced definition signal on a standard 4:3 television you will have black bars above and below the picture.

High Definition (HDTV) - 720p/1080i
High definition is the next step up in signal quality in the digital realm.  We jump from 480 horizontal lines of resolution to 720 lines of resolution.  Now, it gets a touch tricky in that the signal can be either 720p (720 horizontal lines progressively scanned) or 1080i (1,080 horizontal lines interlaced).  However, you need not worry as your display will automatically broadcast the appropriate signal based on the input.  Like enhanced definition, the signal is a native 16:9, wide-screen, aspect ratio, and is nearly twice the resolution of enhanced definition, yielding an exceptionally crisp and clear picture.

Full High Definition (Full HDTV) - 1080p
Full HD displays are becoming much more prevalent in the marketplace as prices continue to come down.  The native input of a full HD signal is double the resolution of regular HDTV, with 1,080 horizontal lines scanned progressively.  Full HD produces the best quality, sharpest picture available with the existing technology. 

HDTV Display Types
There are currently three predominant display types for HDTV.

1. LCD (Liquid Crystal Display) Flat Screen
2. Plasma Flat Screen
3. DLP (Digital Light Processing) Rear Projection

Between the two flat panel options, LCD is generally the better choice in situations where you would have a lot of glare on the screen.  Plasma’s are great for exceptionally bright rooms where the television picture is susceptible to washing out.  As of this writing, DLP displays are generally able to be manufactured larger than the two flat panels, though the gap is closing rapidly.  DLP’s yield exceptional contrast and are very good in situations where glare would be a problem.  When a display is described as being HDTV Built-In it simply means the set is able to convert OTA (over-the-air) digital signals for viewing on the screen.  HDTV Ready means the display is capable of producing a high definition signal, but it requires the use of a set-top box to convert the signal.

OTA signals are digital transmissions of local broadcast stations.  They are generally available in all metropolitan areas, and will be available in all areas by February 2009 as conventional analog signals will cease to exist.  By connecting the signal from an antenna to your OTA input on an HDTV Built-In display you will receive local HD, network, broadcasts with no additional cost.  For help with selecting the type of antenna and setup information for your area, visit www.antennaweb.org. 

chris@clawblog.com

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