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.
Is there any need for 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).
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.
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.
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.
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.
No matter how sophisticated the algorithms are that guesstimate how the additional pixels should look an upscaled SD image isnt as good as an actual true 1080P HD 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 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.
Near HD DVD Players
A DVD players with near HD picture processing isnt the same as one with progressive scan which converts interlaced images into full frames by combining the two fields that make up the frame so that they are both displayed at the same time. This results in more fluid motion, improved vertical resolution and no interlace artifacts such as flickering between lines. Progressive scan uses the existing two A and B fields pixels from each frame to create a full frame but it doesnt generate additional lines or pixels like an upscaler 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.
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.
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.
