Near HD Televisions

You will already be familiar with standard definition television and you will have heard about high definition, but what about 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?

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.

The movement on the picture of a television is created with 25 still frames being displayed successively every second. Each frame is split in to 2 fields that each contains half of the lines that form the picture with the even lines in one field and the odd lines in the other field. The combining of the 2 fields from each frame is called interlacing which produces a full frame. The odd and even fields are shown alternately as the picture is painted or scanned on the screen each at a rate of 25 times per second. The combined display rate of the odd and even fields is 50 times a second which is referred to as 50 Hz.

The resolution of a television is determined by the number of pixels that make up the screen. The more pixels there are in a picture the higher the resolution and usually the sharper the picture that it is able to display. TVs that have a high resolution are called High Definition (HD) TVs.

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.

Near High Definition TVs are produce a near High Definition image from a Standard Definition source using a method called upscaling.

An Upscaler is also referred to as an Upconverter which converts the resolution of a source signal. Upscaler can convert low resolution images to a resolution that fills the screen. When a Full HD 1080P TV, with a resolution of 1920×1080 pixels, receives a signal from a DVD or a Freeview broadcast of 768×576 pixels it has to upscale the image to fill the screen. It does this because the two resolutions are different and if it didnt upscale the image then some parts of the screen wouldnt be filled by the picture and it would be smaller the screen.

The upscaling process is done by the TV using a digital video processing chip which interlaces the input signal and then the advanced algorithms and filters interpolate the picture by creating the missing lines and pixels that are required to fill the screen. This process matches the input resolution with the TVs native resolution.

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.

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.

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?

Is Near HD as good as true 1080P Full HD? No, because it doesnt matter how sophisticated the digital upscaling process is it cant make a SD image the same as a HD image because it has to guess what the missing information is. However the Near HD feature does enhance the picture so that it is closer to the HD image than a SD picture. Whether you should buy an upscaling Near HD TV will depend on how much you are willing to pay to receive HD broadcasts and Blu-Ray Discs, the type of programmes that you watch and how important it is for you to have the best picture possible from whatever source. If you dont buy Blu-ray discs and you dont want to pay a monthly subscription charge to Sky for HD then there isnt much choice available from the BBCs and ITVs Freesat therefore a Near HD product will be right for you. Even if you do watch Sky HD it will work on 720P and also 576i and 480i for standard definition broadcasts and video games which 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.

If you enjoyed this post, make sure you subscribe to my RSS feed!