Every one is already familiar with standard definition television broadcasts. Most people have also heard of high definition but few have heard of Near High Definition.
A Near High Definition is new type of television that manufactures have launched to enhance a SD picture so that it is Near to High Definition.
We already have High Definition so why do we need Near High Definition TVs ?
Whilst there is an increasing amount of HD content available via Sky and Freesat it isnt possible to watch all available programs in High Definition. The only other sources of HD are Blu-ray and downloads from the internet. Furthermore if you arent prepared to pay a monthly subscription or pay for Blu-ray discs then the choice is limited to Freesat or a small selection of On Demand programmes and movies from Virgin Media or Tiscali. With such a limited choice of High Definition content the television manufacturers believe there is a case for near High Definition televisions that upscale the picture to allow you to make the most of your HD television.
What is a Standard Definition picture.
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).
The movement on the picture of a television is created with 25 still frames being displayed successively every second. Each frame is split in to 2 fields that each contains half of the lines that form the picture with the even lines in one field and the odd lines in the other field. The combining of the 2 fields from each frame is called interlacing which produces a full frame. The odd and even fields are shown alternately as the picture is painted or scanned on the screen each at a rate of 25 times per second. The combined display rate of the odd and even fields is 50 times a second which is referred to as 50 Hz.
The number of pixels that make up a picture is known as the resolution. So a television with more pixels will have a higher resolution. Generally the higher the resolution is on a television the sharper the image that it can produce. Televisions with a high resolution are known as High Definition televisions.
High Definition broadcasts in the United Kingdom are at 720P (1280×720 pixels) or 1080i (1920×1080 pixels). If you want to experience HD TV programmes you will need a TV set that is at least HD Ready with a resolution of 720P (1280×720 pixels). There are also higher resolution televisions than HD Ready TVs known as Full HD Ready 1080P (1920×1080 pixels) but there are not any 1080P broadcasts available at present. To benefit from this increased resolution you will have to rely on Blu Ray discs or HD down loads from the web.
The quality of the picture of a Full HD 1080P TV compared to an ordinary SD TV is around five times greater than a standard definition and hence the reason for the terrific image quality.
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 transforms an input signals resolution to the resolution of the TVs screen. Therefore if you have an HD Ready TV (1280×720 pixels) or a Full HD 1080P TV (1920×1080 pixels) and you watch Freeview or a DVD that has a resolution of 768×576 pixels the TV has to upscale the picture to fill the different resolution TV screen. If television didnt have a digital upscaler the image wouldnt fill the screen and there would be areas of the screen that would be black and unused due the resolution mismatch of the HD TVs native resolution and the resolution of the source.
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.
Whilst advanced software algorithms are able to estimate what the extra pixels should display in the upscaled picture it isnt able to turn a Standard Definition image in to a genuine High Definition picture.
The first and only company to launch Near HD TVs at present in the UK is Toshiba with their Resolution + ZV TVs. These will produce a significantly better picture from a SD source than other standard TVs. This is done by means of a Sony PS3 cell processor upscaler which upscales the picture to 1080p.
The image cell processor compares adjoining images which it merges the detail of to improve the image detail. This gives an image that is lucid with rich colours. The extra detail means the image has sharp edge detail with noticeably reduced 3 D noise. Also the blue and green colours are enhanced to compensate for potential clarity losses that can result from upscaling. Also the contrast is improved in dark scenes but the light areas are still as bright. The combined effect of all of these enhancements is that an SD picture is crisper and with sharp edge detail and better texture whilst the flat areas are unchanged.
Near HD DVD Players
Some DVD Players have a feature known as progressive scan that combines the deinterlaced images of the two fields so that they are displayed at the same time to producing the full frame. Progressive scan produces smoother movement, higher vertical resolution and no interlacing artifacts e.g. line flicker. Whilst progressive scan does improve the picture quality it doesnt generate more lines and pixels with more detail as an upscaling DVD player does.
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.
So should you buy a Near HD TV or DVD Player?
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.
Also if you buy a near HD television and at some time in the future more free content becomes available, or you decide you are prepared to pay a monthly subscription for HD, then you wont need to upgrade your TV because it will already be a Full HD 1080p television. The only near HD products that are available in the UK are manufactured by Toshiba with their ZV range of televisions and the XDE DVD player but more manufacturers will have similar products shortly.
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’ televisions and a large selection of AV products at rock bottom prices. For your convenience you may also find these links useful upconverting hd dvd and toshiba big tv
