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Near HD LCD TVs
You will already be familiar with standard definition television and you will have heard about high definition, but what about 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.
Why do you need a near High Definition Television?
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 (576x768 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 (1280x720 pixels) or 1080i (1920x1080 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 (1280x720 pixels). There are also higher resolution televisions than HD Ready TVs known as Full HD Ready 1080P (1920x1080 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.
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.
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 (1280x720 pixels) or a Full HD 1080P TV (1920x1080 pixels) and you watch Freeview or a DVD that has a resolution of 768x576 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.
All LCD and Plasma televisions have an upscaler to accommodate the different resolutions of various sources so that they fill the native resolution of the screen. What is different about a Near HD televisions is that they use a much more powerful processor in the upscaler that allows them to do a much better job than other televisions.
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 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
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.
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 a 768 x 576 image isnt as good as a 1,920x1,080 image and no amount of digital processing will make them the same but a good upscaler is able to produce something that is closer. If you arent prepared to purchase films on Blu-ray, or pay a monthly subscription for high definition channels, and you arent happy with the limited HD content that is available on Freesat then a near HD product is the right choice. It isnt as good as a genuine HD 1080p source but it does deliver noticeable improvements in the picture quality on virtually all content including 480i, 576i, 720p (DVD, Standard Definition TV broadcasts and Video Games) all of which it will upscale 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.
About the Author Armadeus Cornelius is an AV 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 AV products at low prices. For your convenience you may also find these links useful toshiba upconvert dvd players and toshiba online store
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