From The Beginning

Lots of people talk these days about digital television, but very few actually know what is the difference between analog and digital television. Actually the only difference is the way the signal is transmitted. Analog television signal is transmitted very much like radio signals. The video signal of analog television is AM, and the audio is FM. Because of this, there can be annoying interferences in the signal, depending on meteorological conditions or geographical location.

The resolution and image quality are also restricted, because there are certain bandwidths assigned to analog TV channels. The analog signal is the United States follows the NTSC standard. This had been adopted in the 1940′s, and served well since then, but nobody thought at that time that about color television. One major weakness of the NTSC standard is color implementation, so it is no wonder a lot of people call “Never Twice The Same Color” the NTSC standard.

On the other hand digital TV signal is transmitted very similar to computer data: there are two kinds of signal, “on” or “off”. This way, the user either sees an image, or not. Gradual signal loss is an unknown term in the era of digital TV: it has no difference how close or how far away the transmitter is from the television, the viewer either sees the exact image, or sees nothing.

Digital TV format has been designed considering all main factors of television signal: B/W, color and audio can be transmitted as progressive or interlaced signal. Basically this means the signal content has greater integrity and flexibility.

Another advantage is that because digital TV signal consists of “bits”, the same bandwidth one analog TV signal requires can host not only higher quality digital image, but there will be extra space left, which can be used for extra video, audio or text signals.

This way broadcasters using digital technology can supply more features, like surround sound, multiple language audio or text using the same bandwidth a standard analog TV signal requires. Digital TV has one more advantage: it is able to transmit High Definition (HDTV) signal.

Unlike analog TV, digital technology is also able to broadcast programming in a true wide screen (16×9) format. This means the shape of the picture is very much like a movie screen, so the viewers can see a movie just as the director intended to be seen. Those who watch sports can see more action in one camera shot: it is possible to view the entire length of a football field without having the sensation that it is far away from the camera. The 16×9 format means there will be no more black bars on the top and the bottom of the wide screen image.

The United States made the transition to digital broadcasting on June 12, 2009. This means that all analog TV signals went off on that day. After this date, analog TV sets could be used only with an analog-to-digital converter connected to them. The preparations for transition from the analog to digital took quite some time for the consumers, broadcasters and authorities. The transition was originally planned for 2006, but authorities decided to postpone it because they thought consumers were not ready yet to embrace the new technology.

Edward is an electronics expert who writes HDTV reviews. To read more sharp hdtv reviews, visit HDTVReviewLab.com

Most people are aware of High Definition (HD) even if they still have a Standard Definition (SD) television. But now there is another alternative that is called Near High Definition.

Near High Definition is a new feature that television producers have created for raising the picture quality of Standard Definition (SD) broadcasts to a claimed Near HD quality.

Why do you need a near High Definition Television?

High definition broadcasts arent available on normal terrestrial analogue or digital broadcasts such as Freeview. The only broadcaster that provides limited HD content free of charge at present is the BBCs and ITVs Freesat broadcasts. Sky has the most HD channels but you have to pay a monthly subscription charge. The chances are that you will still watch standard definition broadcasts because not all programmes are available in HD. Alternative sources of HD are Blu-ray discs, download from the web or On-Demand services from Virgin Medias Cable serve or Tisclai. Because the options for watching HD are restricted producers believe that upscaling televisions with Near High Definition pictures will allow people to take advantage of the potential of HD television sets using a SD source.

Standard Definition Broadcasts

The picture on an LCD or Plasma television is made of many thousands of pixels. In the UK the television system is known as Pal which is broadcast with 576 hozontal lines of 768 pixels (576×768 pixels).

A moving television picture is created by showing a series of 25 still frames every second. Each frame contains a still image with slight changes from frame to frame. Each of these frames is divided into two fields, one of which contains all of the odd lines and the other all of the even lines. The displaying of a moving picture using these fields is known as deinterlacing where the two fields of a single frame are combined to form a full frame. The odd fields and the even fields are alternately painted or scanned on to the TV screen each at a rate of 25 fields a second or 50 fields a second when combined. This is where the term a 50 Hz picture has comes from.

The resolution of a television is determined by the number of pixels that make up the screen. The more pixels there are in a picture the higher the resolution and usually the sharper the picture that it is able to display. TVs that have a high resolution are called High Definition (HD) TVs.

All UK high definition broadcasts are either at 720 p (1280pixels x 720pixels) or 1080i (1920pixels x 1080pixels). You will need a television of a specification of at least HD Ready which will be able to display a 720P broadcast. There arent any broadcasts of 1080 P ( 1920pixels x 1080pixels ) material in the UK at this moment in time. To take advantage of the full reolution of a 1080P tv set you will have to view either Blu-Ray discs or downloads from the internet.

A Full HD Ready 1080p television has a picture resolution that is about 5 times the resolution of a Standard Definition television. This is why with suitable source material a Full HD television has such a stunning picture.

So how are near High Definition images created from Standard Definition? A process known as upscaling is used to create a near HD image. But what is upscaling?

An Upscaler is also referred to as an Upconverter which converts the resolution of a source signal. Upscaler can convert low resolution images to a resolution that fills the screen. When a Full HD 1080P TV, with a resolution of 1920×1080 pixels, receives a signal from a DVD or a Freeview broadcast of 768×576 pixels it has to upscale the image to fill the screen. It does this because the two resolutions are different and if it didnt upscale the image then some parts of the screen wouldnt be filled by the picture and it would be smaller the screen.

HD televisions have a video processing chip that upscales the image so that the incoming picture signal has the same resolution as the native resolution of the screen. This is done by first interlacing the picture which allows the digital algorithms and filters to interpolate the image by adding extra pixels and lines.

The ability of a TV to upscale an image is dependant on how good the source input and the quality of upscaler chip. The quality of upscaling chips varies from TV to TV as does the quality of other internal components and the actual screen which affect the quality of the picture displayed.

An upscaler is required by all LCD and Plasma TVs so that they are compatible with the various source resolutions that they may be presented with so that they fill the native resolution of the screen. It may seem that the Near HD TVs arent doing anything different to any other LCD or Plasma TV but it is how they do it that is different. The Near HD TVs use a more powerful upscaling processor chip which means that they are much better at upscaling than ordinary TVs.

The higher quality upscaling chip employs sophisticated software algorithms that approximate how the additional created pixels should look in the upscaled image. However this approximation isnt as good as a Full HD sourced image where the TV doesnt have to guess what the extra pixels look like. Any approximations will sometimes be inaccurate but an educated guess.

Toshiba has a near HD upscaling technology called Resolution + which they incorporate in their ZV range of televisions that they say will vastly improve the quality of a Standard Definition picture. They use the powerful upscaling cell processor that is used in the Sony PS3 which upscales any image to 1080p resolution.

The enhanced picture is achieved by the cell processor comparing adjacent image frames which it then combines the pixel detail of to enhance the definition. The picture quality is clearer with sharper and richer pictures. The detail is enhanced which sharpens the edge of images and reduces 3D noise. The colour palette is more natural due to enhancement of the blue and green shades minimizing the loss of clarity that upscaling can often cause. Contrast Enhancement results in dark areas becoming darker whilst at the same time the bright areas maintain their brightness. This results in Standard Definition images being crisp and rich with sharper edges and improved texture but the flat areas are not changed.

Upscaling Near HD DVD Players

Near HD differs to progressive scan which combines two interlaced field images into full frames which are together displayed at the same time giving smoother motion. Also this enhances the vertical resolution and prevents artifacts such as line flicker which is flickering between the lines. Whilst progressive scan uses the 2 fields of a frame to produce a full frame it doesnt create extra lines and pixels in the way that upscalers do.

An upscaling DVD player uses the same methods as an upscaling television. There are a number of upscaling DVD players from different manufacturers but non of these work in the same way as the Toshiba XDE model which deinterlaces the picture before upscaling it from 576i lines to 1080P Near High Definition quality. The picture on the Toshiba upscaling DVD player is improved with images that are extra detailed with brilliant colours and enhanced contrast by employing the methods used on the Toshiba Near HD TVs.

Is near HD worth buying?

Obviously an upscaled SD 576 line picture is not as good as a 1080P Full HD picture no matter how much digital processing is done. Nonetheless there is no doubt that a much better upscaler in a television produces a noticeable improvement in the picture quality so that it is closer to 1080P picture. A Near HD TV makes even more sense if you arent willing to pay a monthly charge for HD from Sky, Virgin Medias Cable, Tiscalis Service or Blu-Ray discs. Even if you opt for Freesat there is a limited amount of HD channels available so your choice of programmes is limited. Because HD isnt freely available, especially with out paying for it, a Near HD TV is worth considering that will produce an improved picture with virtually any content including 480i, 576i, 720p as well as DVD, Standard Definition Broadcasts and computer games. With all of these sources the picture will be upscaled to 1080P.

The Near HD TVs offer the ultimate flexibility with the ability to enhance almost any source. As more HD options become available either chargeable or free the TV is capable of receiving and displaying 1080P sources so you wont need to upgrade your TV. Toshiba is the only company that offers Near HD TVs and a DVD Player but others will follow soon.

Armadeus Cornelius is an AV enthusiast and expert with nearly 2 decades experience in consumer electronics. His website at www.digitaldirect.co.uk offers ‘Near HD’ TVsand a large selection of AV products at low prices. For your convenience you may also find these links useful toshiba upconverting dvd recorder and toshiba outlet