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.
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 a Standard Definition picture.
A TV picture consists of 1000s of little cells known as pixels. Broadcasts in the UK use the PAL system which in standard definition has 576 horizontal lines of 768 pixels across the screen or 768 x 576 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.
All UK high definition broadcasts are either at 720 p (1280pixels x 720pixels) or 1080i (1920pixels x 1080pixels). You will need a television of a specification of at least HD Ready which will be able to display a 720P broadcast. There arent any broadcasts of 1080 P ( 1920pixels x 1080pixels ) material in the UK at this moment in time. To take advantage of the full reolution of a 1080P tv set you will have to view either Blu-Ray discs or downloads from 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.
Near High Definition TVs are produce a near High Definition image from a Standard Definition source using a method called upscaling.
Upscaling or Upconverting is the process of converting a signal from one resolution to another. So when you view a DVD or Freeview with a resolution of 768 – 576 on a HD Ready Television or a Full HD 1080p Television with a resolution of 1920 x 1080 if there wasnt any digital upscaling done by the television then the picture wouldnt fill the screen and there would be large areas of black. The reason for this is that the resolution of the DVD or Freeview isnt the same as the native resolution of the HD television screen so many of the pixels wouldnt be used by the smaller image.
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 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.
Different sources of programmes and films are available at different resolutions that dont match the resolution of a television screen. Ordinarily a TV that received sources with a resolution that is different to its own native resolution would have areas of the screen without any picture information on it. To get around this problem all LCD and Plasma televisions have an upscaler that matches the source resolution to the TV screen so that the image fills the screen. A Near High Definition TV has a much powerful upscaling processor chip that is capable of producing a better quality upscaled image 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.
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.
DVD Players with Near HD
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.
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.