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.

This is a term that is used by Television manufacturers for a system that enhances the quality of Standard Definition pictures on televisions to near High Definition.

Is there any need for a Near High Definition Television?

There has never been so much choice of HD programmes and movies. Both Sky and the BBCs and ITVs Freesat provide multiple channels of HD. Alternatives to these are Blu-Ray, HD downloads on the Web, or On Demand services from Virgin Media or Tiscali. It might appear as if there is a lot of choice but it still isnt possible to watch all channels in HD. If you arent prepared to pay a monthly subscription fee then Sky isnt an option and your choice will be narrowed considerably because they have the most choice of channels. Furthermore if you dont want to buy or hire Blu-Ray Discs the choice is even more limited leaving 2 channels of free HD channels on Freesat or a small amount of On Demand programmes or films from Tiscali or Virgin Media. Because of these limitations on available HD programmes the television manufacturers believe that there is a need for Near High Definition 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).

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 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.

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 quality of the upscaled image thats displayed will be determined by the quality of the upscalers processing chip, other electronics and the screen. The source signal quality will also be very important in determining how the internal electronics manage the picture and how they well they display it.

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.

Toshiba have a range of TVs that use the cell processor from the Sony PS3 to upscale the image to the Near HD 1080P resolution. Toshiba have called this feature Resolution + which is featured in their ZV series of TVs. This feature vastly improves the picture quality of a SD picture source.

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

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.

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.

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.

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