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.
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 Standard Definition?
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).
When a television picture is broadcast the moving picture is broken down in to frames. These frames are actually split in to two half fields A and B, where the A field consists of the odd lines and the B frame consists of the even lines. This type of picture is known as an interlaced image. When the two fields of each frame are combined or interlaced they create a complete frame as each field is alternately scanned or painted onto the television screen. Where the odd and even fields are displayed alternately each showing 25 times a second or 50 times a second when displayed alternately together, hence the term a 50hz picture.
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.
At present UK broadcasts of HD content are at 720p (1280 pixels x 720 pixels) or 1080i (1920 pixels -1080 pixels) resolution. To benefit from this you will need a television that is at least HD Ready with 720p (1280 pixels x 720 pixels). Alternatively you can buy a Full HD Ready 1080p (1920 pixels x 1080 pixels) television although there arent any broadcasts that will allow you to benefit fully from this specification. The only source that is available is either Blu-ray disc or downloads via the internet.
With suitable source material a Full HD Ready 1080P TV has a picture resolution thats five times higher than a SD TV which explains why the picture is so much better.
On TVs that have Near HD they use an upscaler to transform an SD picture into 1080P.
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.
The upscaling in a HD TV is performed by a video processing chip which first interlaces the fields of the frames that create the picture using complex digital algorithms and filters that interpolate the picture by estimating what the extra pixels and lines should look like. This is done to match the incoming signal resolution with the native resolution of the TV.
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.
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 cell processor compares neighbouring frames and aggregates the pixel detail to raise the definition of the picture. The effect of this is that the picture has sharper image edges with subdued 3-D noise. Furthermore the colour palette is more lifelike because the blue and greens are improved to minimise the loss of clearness that can be caused by an upscaler. Also due to the contrast being enhanced the dark areas are even darker but the light areas sustain their luminance. The SD images are crisp and rich and have sharp edge detail with improved texture however the flat areas are not changed.
DVD Players with Near HD
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.
There is a number of upscaling DVD players presently available on the market. These machines dont deinterlace the image before upscaling it from SD. Only Toshiba currently has an upscaling Near HD DVD Player, the XDE model, that upscales the SD 576 line picture to 1080P lines Near HD. This is done in a similar way to the Resolution + TVs from Toshiba where the picture is enhanced so that it is more detailed with lifelike colours and better contrast levels.
Should you buy Near HD TVs and DVD Players?
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.
A further benefit of purchasing a Near HD TV is that if more free HD content becomes accessible in the future or if you subscribe to Skys HD service then you will not need to buy a HD TV because the Near HD TVs are also Full HD 1080P TVs. In the United Kingdom the only Near HD products that are currently available are made by Toshiba but other products will be launched by alternative manufacturers soon.
Armadeus Cornelius is an Home Entertainment enthusiast and expert with nearly 20 years experience in consumer electronics. His website at www.digitaldirect.co.uk offers ‘Near HD’ televisions and a large selection of Home Entertainment products at rock bottom prices. For your convenience you may also find these links useful upconverting dvd and toshiba uk
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