HDTV: The Reality

This content is several years old but is still relevant if nothing else as a history lesson in how misinformed consumers often find themselves. Myth#3 is the most outdated because more HDTV content is available. The price and quality of Plasma Televisions has improved dramatically in the last few years and is generally considered the best option for HDTV viewing.

Myth #1 - Everyone must get a new TV

Everyone will not have to buy a NEW TV in a few years. If you have a satellite system, or cable set-top box your TV will continue to work just fine. The satellite receiver and cable set-top box already convert digital signals to a signal your TV can process. If you use a Roof-Top antenna as your only source for TV signals, then you will need a converter when the over-air broadcasters switch to digital signals starting in 2009. These converter are not yet readily available, but they should start showing up in 2008. The television stores are not going to be pushing this option, because they want you to buy a new TV, not a low profit converter. If you are using Satellite TV, then your satellite receiver IS your converter. If you are using a cable TV set-top box you also already have a converter.

Myth #2 - All channels are switching to HDTV

In 2009 all television channel will NOT be High Definition. There is no mandate by any government agency that all television channels convert to HD. The only FCC requirement is that over-the-air broadcasters switch to a digital format. Broadcasters will have two options. They can switch to a single High-Definition broadcast, or they can broadcast two standard definition digital signals. Most will choose the HDTV option, but not all. There is no requirement that Cable and Satellite only channels such as CNN, Home and Garden, Travel Channel ect... switch to HD format. These channels, and most, will eventually switch to HD format, but they will do so from market forces, not federal regulations.

Myth #3 - High Definition Televisions always produce a better picture.

This is perhaps the most grievous of myth that affects consumers the most. You go out and by a new 50" Plasma, LCD, or DLP television, get it home, hook it up to your cable or satellite set-top box, and stand there wondering why your picture is worse than your older 36 inch tube television. A HDTV will produce a better picture when you watch a HDTV channel, but will often look worse when you are watching a non-HD channel , aka Standard Definition or SD.

 

In reality, digital cable and all small dish satellite systems compress the digital image, thus reducing image clarity. Your older TV was unable to "see" or reproduce the image defects and therefore you never new the defects were present. Your new digital processing High Definition television is able to "see" and reproduce the image defects.

Much of the problem has to do with the digital processor within the televisions. These processors are commonly known as the "Engine". The engine processes the television image for displaying on the display surface. Many Plasma and LCD televisions use screens from a single manufacturer. Each television will produce a difference image based on the engine controlling the display. Sony heavily promotes their "WEGA" engine.

 

...DLP televisions are better at producing a decent picture....

It is the opinion this home theater technician, that DLP televisions are better at producing a decent picture when viewing non-HD television channels. There is nothing wrong with Plasmas or LCD's, it is just my opinion that DLP's produce a more natural look. The real world is not as dark, white, red, blue or as clear as some of these TV's represent. A television image should be natural and not some image pumped up on digital steroids to make it unnaturally clear.

Myth #4 - Digital is always better than Analog

Digital is NOT always better than analog. It is cheaper, it allows more television channels to be broadcast with in a given bandwidth, and it is capable of transferring any media between two locations without loosing image quality. The problem is it also has some problems. With an analog signal, a weak signal produces perhaps a bad, but still watchable image. With digital, a signal level below a minimum threshold produces no image. Analog signals are uncompressed video. Digital signals can be uncompressed, but they are not.

 

To increase channel capacity, both Cable TV and Satellite compress their digital channels. This compression is similar to when you save a digital picture on your computer or digital camera. If you save a picture in a Bitmap format. The file size is very large, but the image remains in its original, uncompressed format. However, if you save an image in a JPEG format, you loose image quality. The amount of image quality degradation when using JPEG is incredibly small. Some compression is just fine for everyday use. Too much compression to save disk space produces a lower image quality.

Compressed image at an acceptable level.

Fig 1.

Fig 1 represents a compressed image that still maintains an acceptable picture quality.

 

Compressed image zoomed in.

Fig 2.

Fig 2 is the same imaged zoomed in. Notice the minor degradation around the eyes and the orange windows on the ginger bread house. Most people would consider this level of compression acceptable. Unless you stand right in front of your TV, or if you have a large TV in a small room, this picture quality would be fine. The problems start when you view this image on a HI-DEF television. Even though the image is the same, the HDTV has the ability to show more detail.

Compressed image zoomed in.

Fig 3.

Fig 3 represents the same image when viewed on a HDTV. It looks worse because now you can see the results of high compression. The smoothness of the ginger bread walls becomes blotchy. The transitions from dark to light along the white frosting become muddy.

This is what happens when you view standard definition channels on a HDTV. In reality even a SD television can show the problems of over compression.

 

Until a majority of the channels you watch are in HDTV format, you may have to live with some image quality issues.

If you do not have access to HD digital cable, HD satellite TV, or can receive over-the-air HDTV broadcast (consult with a local television store), do not waste your money on a new High Definition Television unless you really need a new TV. If you do get a knew HDTV, you should also plan to upgrade your television signal to a service that provides HDTV, or use a roof top antenna for HD reception. Consult with a local HDTV technician to see if your area can receive over the air HDTV.

 

The final example of why digital is not always better than analog can be explained this way. Given a telegraph reaching 10 miles across a town or a set of CB radios with a 20 mile range placed 10 miles apart, which option would you think provides the best method of communication?

 

If you said the CB radio, then you just selected an analog signal over a digital means of communication. Telegraphs use morse code, which is a form of digital communications. Telegraphs only use 1 bit of bandwidth, which is the smallest possible, but telegraphs are still digital. A telegraphs signal can be exactly reproduced over any distance. Of course the analog CB radio would be better in this example, but to say digital is always better than analog is incorrect. Factors such as bandwidth and compression ratios must be factored in to the equation.

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