What is the BBC's and ITV's Freesat ?
Freesat has in excess of 140 channels of digital Radio and Television without any contract or monthly charges, and there are more channels to come. All that is necessary is the purchase of the receiving equipment. The BBC and ITV joined together to make available this service as an alternative to Sky Satellite, Freeview and Cable. It provides pictures and sound that are crystal clear and almost perfect. As you would expect there is also an 8 day on screen programme guide and teletext.
What equipment is required to receive Freesat ?
Either a set top box in cunjuction with a television, or a television with a Free sat receiver built in is required to receive Freesat. Set top boxes are obtainable in standard definition and high definition and some contain a built in PVR hard drives to record programmes. If you choose to buy a television with Freesat built in then you won’t require a Freesat set top box. Panasonic is at present the only manufacturer of Freesat televisions. There are two LCD models available, TX32LZD81 and TX37LZD81; and there are three Plasma TV models, TH42PZ81B, TH46PZ81, and TH50PZ81B.
Whether you use a Freesat set top box or a television with Freesat built in you will also require a satellite mini dish. If you already have an existing sky satellite mini dish that is unused, or if have one being used for sky and it has an unused connector on the LNB, it follows that you won’t need to instal another dish. If you don’t have any free connectors on the LNB then a Satellite dish installer might be able to upgrade it so that it has two or four connectors. A satellite dish installer will also be required to instal a satellite dish if you don’t have one, or you need an additional one, or if you require additional cable runs from an unused LNB connector. Clearly the fittingof a satellite dish is dependant on the dish having no obstructions such as trees, and also subject to limitations such as planning issues or high rise buildings.
Which parts of the country can receive Freesat ?
Approximately 98 per cent of households are capable of receiving Freesat even if they don't at this time receive Freeview via normal broadcasts.
What types of programme channels are offered ?
There is a diverse range of programme categories such as Sports, News, Lifestyle, Childrens channels, Entertainment, Music, Special Interests, Movies, Dating, Regional television, Gaming and Shopping, as well as digital Radio. With quality channels from ITV and the BBC including BBC1, BBC2, BBC3, BBC4, BBC News, BBC Parliament, Channel 4, Zone Thriller, E4, Zone Reality, Zone Romanitica, Zone Horror, Pop Girls, Pop, CITV, KiX, Film 4, Movies for Men, Movies 4 Men 2, B4U, Music, QVC, Zmusic, Price-Drop TV, JML, etc. Whats more there are additional channels due to come shortly.
Can you receive high definition TV on Freesat ?
HD channels are accessible on Freesat without any further charges other than the cost of the HD set top box and a HD Ready television or a Freesat HD Ready television. The benefit of a high definition picture is an increase in the picture resolution by roughly five times that of a standard picture resolution giving more vivid and detailed pictures.
Currently there is limited availability of high definition TV channels on Freesat with only BBC HD and . Neither of these channels offer high definition all day however the amount of time will be greater in 2009.
If you own a HD Ready Television and don’t have Virgin's HD Cable or Sky HD then Freesat offers a means of getting the most from the capabilities of your TV with no monthly charges.
Interactive TV - a new way of viewing television.
At the press of the red button you will have access, via user friendly menus, to lottery results, news headlines, the weather, business news etc.
There are also video based multi-screen interactive television services, which allow you to choose which cameras you view on selected programmes or events, again by pressing the red button. This is available on events such as Glastonbury, Wimbledon, the Olympics, Snooker, the Proms, etc. So you will be able to choose which court you view at Wimbledon, or which snooker table, stage, event ,etc on other events. This feature will be obtainable on an increasing amount of events in the future.
Conclusion
With freeview even now not available in all areas of the country Freesat is an ideal choice that doesn't require a monthly payment or agreement. The only other option is the free channel option from Sky but that doesn't boast any free of charge high definition channels. If you don't intend to pay a monthly charge and you would like to receive HD TV then Freesat is probably the only alternative for the next few years.
Sunday 7 December 2008
Monday 24 November 2008
LCD or Plasma TV - Which is the best?
What is the difference between LCD and Plasma Televisions?
Comparison of the flat screen tv technologies
When it comes to flat screen TVs the two technologies LCD and Plasma look very similar with almost lifelike images and the ability to be hung on the wall. Although LCD tvs and Plasma tv panels may look very similar in the shops, there are various differences between the two technologies.
How LCD tvs work
LCD means Liquid Crystal Display. The LCD tv screen is a thin, flat display device comprised of two clear panels that have a number of colour liquid crystal-filled pixels arrayed between them. The crystals twist or untwist and reposition themselves to either let light pass through or block light and this results in a picture being displayed when millions of crystals do this concurrently. The reposition of the crystals is triggered by a small voltage and uses very little power. The LCD tv screen is backlit so this behaviour creates light or dark spots on the screen and colour depending on the pixels that are repositioned. LCD tvs are available in sizes from a few inches to over 108 inches. All top manufacturers have LCD televisions including Sony, Panasonic, Philips, JVC, Toshiba, Hitachi, Samsung, LG, Pioneer and Sharp.
How plasma tvs works
A Plasma tv screen comprises of millions of minuscule 'light bulbs' which are tiny glass cells filled with inert gases such as xenon and neon. These cells are illuminated by a current being applied to electrodes in the gas filled cell and its atoms become 'excited' to a plasma and emit photons of ultraviolet light. These photons in turn hit a phosphor coating which emits visible light. The colour of the visible light emitted by each cell depends on the three different coloured phosphors - red, blue and green, and can together make billions of colours when combined. As with the LCD tv screen, the millions of cells intermix to form the image on the screen. Currently the only manufacturers of Plasma tvs in the UK are Panasonic, Pioneer, Philips, LG, and Samsung. Plasma tvs are available in sizes from 32 inches to 150 inches.
Performance and Picture quality compared
Brightness
LCD TVs can be brighter than plasma TVs. This perception of this brightness is of course reliant on where the TV is situated and what is being watched. In reality both technologies are capable of producing a level of brightness that is in excess of what is needed in normal viewing.
Contrast Ratio and Black Levels
The contrast ratio is a measure of the difference in light and dark tones that a panel can produce - in general a high ratio means greater details can be discerned. Historically LCD tv panels have had a lower contrast ratio than plasma tvs because the backlight bleeds through darkened pixels and lightens the image. Recent advances in technology have produced techniques to thwart light leakage, and improvecontrast ratios so that they are more comparable with Plasma tv, but still not as good. Because each cell on a plasma tv is able to be switched off rather than blocking the light as per LCD tvs the blacks are blacker. For a television picture, the black level is very important because black encompasses the entire spectrum of colour. Thus the deepest blacks create the richest colours and thus more realism. Without deep black levels the colours look more 'pastel' like. Typically the black on an LCD tv screen is more 'grey' when compared to the plasma tvs black.
Colour Saturation
This is a gauge of the correctness of the colours on the screen based on the presence of grey shades - the higher grey shades results in lower colour saturation. Plasma TVs have high colour saturation due to the way they emit light. The capability of Plasma tv pixels to be switched off when they are not in use stops the emission of stray light that diffuses colour. This is why tints and hues on Plasma TVs are noticeably more vivid and vibrant
Colour Gamut
Is the breadth and amount of colours that can be displayed. The most expensive models are now claiming to have colour gamut's getting quite close to the full spectrum for plasma tv and LCD tv. In fact most plasma TVs tend to be better than most LCD tvs apart from the top of the range ones. With the cheapest LCD tv models more often than not offering a colour gamut that isn’t as good the higher LCD tv models. So as a rule the plasma tv has the best colour gamut.
Resolution
This is the quantity of pixels that make up the screen. The higher the resolution is, the higher the definition and the sharper picture is. Currently, LCD HDTV’s create the image at 1920 pixels x 1080 pixels, full 1080p resolution at a lower cost than plasma tv panels of the same size. There is no difference in an HD LCD tv or Plasma tv for screen sizes above 37 inches. Though plasma tv screens of 37 inches and below are at present only HD Ready but LCD tv models are available from 32 inches upwards in full HD or 1080P.
Response Time and Refresh Rate
These two attributes in combination establish how fast a moving picture a screen can reproduces without the image blurring. Response time is a measure of how quickly a screen can vary when an input is received. Historically LCD tv panels had slow response times which was the limiting factor causing motion blur because each pixel has to go from an on state, to an off state, and back to on in order to refresh an image. Improvements in pixel response times on LCD tv screens means that the actual response time isn't the main cause of motion blur, its mostly caused by the refresh rate, or the frame rate.
All LCD tvs and Plasma tvs have until of late had frame rates of 50 frames per second or 50hz. The more expensive LCD tv and Plasma tv models now have 100 Hz to compensate for any motion blur. Since the normalsignal is only 50 Hz the additional frames are created with signal processing software which interpolates what the add-on middle frames ought to look like. The consequence is moving pictures that loose hardly any definition and are more fluid. The best Plasma tv screens nonetheless respond better to rapid motion than LCD tv but the difference has lessened as the best LCD tvs motion response time has improved and 100hz and 200hz has been introduced.
Viewing Angle
Pictures on plasma TVs are nevertheless clearly viewable at about 160 degrees and on some models up to 180 degrees. the picture dulls further than about 100 degrees.
The screen surface of lcd tvs and plasma tvs
LCD tv screens are available with matt finish screens which lessen glare whereas Plasma tvs have a reflective screen.
Burn-in
This can result if a static image is displayed on the screen for an extended time, and even once the image is changed or removed, the 'ghost image' of the previously displayed static image is still visible on the screen for the rest of the screens life. burn-in doesn’t take place on LCD tvs. Though the expose of burn-in on plasma tv is usually exaggerated and not likely.
Image retention
A lot of people mix up burn-in with image retention which is very similar. With image retention the 'ghost image' disappears quickly either once a new, bright image is displayed or after a few seconds. image retention is infrequently noticed but normal on plasma tvs because of the technology used, but it can be minimised by having a 'break-in' period when the plasma tv is first bought. The break-in period normally lasts 100 hours, during this time you shouldn't view any programs that don't fill in the whole screen, and you should notview any programmingthat have static images such as bright station logos or news scrolls at the bottom of screens, and you should lower the contrast and brightness to a mid level. Nowadays there are also features built in to the plasma tvs to decrease the possibility of either burn-in or image retention.
Power consumption
LCD tvs have a backlight that is alwayson and uses virtually constant power. LCD tvs usually have an adjustable back light which uses more power when it is on a high setting and not as much of on a low setting. The power required to alter the pixels is infinitesimal.
But Plasma tvs charge a gas to a plasma to create light. The more light that is required the more often this is done. So it's normal for plasma tvs to require more energy on an image with high levels of brightness, and less energy on low brightness scenes. Accordingly the power consumption varies.
On paper it might appear that the Plasma tvs employ a lot more power than LCD tvs. Plasma tv manufacturers tend to quote the highest power usage at full brightness. However the plasma tvs power power consumption varies depending on the signal and the amount dark and bright areas on the screen. Studies have revealed that when watching mainly dark programs and movies the average power power consumption of an identical sized plasma tv is really lower than LCD tv. However if lots of cartoons and sport are viewed then the LCD tv uses less power. Consequently on average with varied viewing content there is little difference between LCD tvs and Plasma tvs. Plasma tv manufacturers are shortly going to be launching models that will cut the power consumption by over half.
Life expectancy
Plasma tv manufacturers are nowadays quoting statistics of 100000 hours for the life expectancy. This represents a usage level of almost 11.5 years of non stop use. Thus any concerns concerning the life expectancy of plasma tvs being less than LCD tvs are unfounded.
Conclusion
Both technologies have benefits. Plasmas tvs typically have a better subjective picture with better black level, higher contrast, and superior colour rendering than LCD TVs. While LCD TVs have higher brightness, freedom from screen burn-in worries, and are lighter and thinner. This is not always the case becausea good LCD TV could have a better picture than an middling or poor plasma TV. Nevertheless on balance I consider that a plasma tv is the superior option with extra advantages. In the end you get what you pay for so spend as much as you can find the money for on you preferred format.
For more information go to Discount LCD TV and Discount Plasma TV
Comparison of the flat screen tv technologies
When it comes to flat screen TVs the two technologies LCD and Plasma look very similar with almost lifelike images and the ability to be hung on the wall. Although LCD tvs and Plasma tv panels may look very similar in the shops, there are various differences between the two technologies.
How LCD tvs work
LCD means Liquid Crystal Display. The LCD tv screen is a thin, flat display device comprised of two clear panels that have a number of colour liquid crystal-filled pixels arrayed between them. The crystals twist or untwist and reposition themselves to either let light pass through or block light and this results in a picture being displayed when millions of crystals do this concurrently. The reposition of the crystals is triggered by a small voltage and uses very little power. The LCD tv screen is backlit so this behaviour creates light or dark spots on the screen and colour depending on the pixels that are repositioned. LCD tvs are available in sizes from a few inches to over 108 inches. All top manufacturers have LCD televisions including Sony, Panasonic, Philips, JVC, Toshiba, Hitachi, Samsung, LG, Pioneer and Sharp.
How plasma tvs works
A Plasma tv screen comprises of millions of minuscule 'light bulbs' which are tiny glass cells filled with inert gases such as xenon and neon. These cells are illuminated by a current being applied to electrodes in the gas filled cell and its atoms become 'excited' to a plasma and emit photons of ultraviolet light. These photons in turn hit a phosphor coating which emits visible light. The colour of the visible light emitted by each cell depends on the three different coloured phosphors - red, blue and green, and can together make billions of colours when combined. As with the LCD tv screen, the millions of cells intermix to form the image on the screen. Currently the only manufacturers of Plasma tvs in the UK are Panasonic, Pioneer, Philips, LG, and Samsung. Plasma tvs are available in sizes from 32 inches to 150 inches.
Performance and Picture quality compared
Brightness
LCD TVs can be brighter than plasma TVs. This perception of this brightness is of course reliant on where the TV is situated and what is being watched. In reality both technologies are capable of producing a level of brightness that is in excess of what is needed in normal viewing.
Contrast Ratio and Black Levels
The contrast ratio is a measure of the difference in light and dark tones that a panel can produce - in general a high ratio means greater details can be discerned. Historically LCD tv panels have had a lower contrast ratio than plasma tvs because the backlight bleeds through darkened pixels and lightens the image. Recent advances in technology have produced techniques to thwart light leakage, and improvecontrast ratios so that they are more comparable with Plasma tv, but still not as good. Because each cell on a plasma tv is able to be switched off rather than blocking the light as per LCD tvs the blacks are blacker. For a television picture, the black level is very important because black encompasses the entire spectrum of colour. Thus the deepest blacks create the richest colours and thus more realism. Without deep black levels the colours look more 'pastel' like. Typically the black on an LCD tv screen is more 'grey' when compared to the plasma tvs black.
Colour Saturation
This is a gauge of the correctness of the colours on the screen based on the presence of grey shades - the higher grey shades results in lower colour saturation. Plasma TVs have high colour saturation due to the way they emit light. The capability of Plasma tv pixels to be switched off when they are not in use stops the emission of stray light that diffuses colour. This is why tints and hues on Plasma TVs are noticeably more vivid and vibrant
Colour Gamut
Is the breadth and amount of colours that can be displayed. The most expensive models are now claiming to have colour gamut's getting quite close to the full spectrum for plasma tv and LCD tv. In fact most plasma TVs tend to be better than most LCD tvs apart from the top of the range ones. With the cheapest LCD tv models more often than not offering a colour gamut that isn’t as good the higher LCD tv models. So as a rule the plasma tv has the best colour gamut.
Resolution
This is the quantity of pixels that make up the screen. The higher the resolution is, the higher the definition and the sharper picture is. Currently, LCD HDTV’s create the image at 1920 pixels x 1080 pixels, full 1080p resolution at a lower cost than plasma tv panels of the same size. There is no difference in an HD LCD tv or Plasma tv for screen sizes above 37 inches. Though plasma tv screens of 37 inches and below are at present only HD Ready but LCD tv models are available from 32 inches upwards in full HD or 1080P.
Response Time and Refresh Rate
These two attributes in combination establish how fast a moving picture a screen can reproduces without the image blurring. Response time is a measure of how quickly a screen can vary when an input is received. Historically LCD tv panels had slow response times which was the limiting factor causing motion blur because each pixel has to go from an on state, to an off state, and back to on in order to refresh an image. Improvements in pixel response times on LCD tv screens means that the actual response time isn't the main cause of motion blur, its mostly caused by the refresh rate, or the frame rate.
All LCD tvs and Plasma tvs have until of late had frame rates of 50 frames per second or 50hz. The more expensive LCD tv and Plasma tv models now have 100 Hz to compensate for any motion blur. Since the normalsignal is only 50 Hz the additional frames are created with signal processing software which interpolates what the add-on middle frames ought to look like. The consequence is moving pictures that loose hardly any definition and are more fluid. The best Plasma tv screens nonetheless respond better to rapid motion than LCD tv but the difference has lessened as the best LCD tvs motion response time has improved and 100hz and 200hz has been introduced.
Viewing Angle
Pictures on plasma TVs are nevertheless clearly viewable at about 160 degrees and on some models up to 180 degrees. the picture dulls further than about 100 degrees.
The screen surface of lcd tvs and plasma tvs
LCD tv screens are available with matt finish screens which lessen glare whereas Plasma tvs have a reflective screen.
Burn-in
This can result if a static image is displayed on the screen for an extended time, and even once the image is changed or removed, the 'ghost image' of the previously displayed static image is still visible on the screen for the rest of the screens life. burn-in doesn’t take place on LCD tvs. Though the expose of burn-in on plasma tv is usually exaggerated and not likely.
Image retention
A lot of people mix up burn-in with image retention which is very similar. With image retention the 'ghost image' disappears quickly either once a new, bright image is displayed or after a few seconds. image retention is infrequently noticed but normal on plasma tvs because of the technology used, but it can be minimised by having a 'break-in' period when the plasma tv is first bought. The break-in period normally lasts 100 hours, during this time you shouldn't view any programs that don't fill in the whole screen, and you should notview any programmingthat have static images such as bright station logos or news scrolls at the bottom of screens, and you should lower the contrast and brightness to a mid level. Nowadays there are also features built in to the plasma tvs to decrease the possibility of either burn-in or image retention.
Power consumption
LCD tvs have a backlight that is alwayson and uses virtually constant power. LCD tvs usually have an adjustable back light which uses more power when it is on a high setting and not as much of on a low setting. The power required to alter the pixels is infinitesimal.
But Plasma tvs charge a gas to a plasma to create light. The more light that is required the more often this is done. So it's normal for plasma tvs to require more energy on an image with high levels of brightness, and less energy on low brightness scenes. Accordingly the power consumption varies.
On paper it might appear that the Plasma tvs employ a lot more power than LCD tvs. Plasma tv manufacturers tend to quote the highest power usage at full brightness. However the plasma tvs power power consumption varies depending on the signal and the amount dark and bright areas on the screen. Studies have revealed that when watching mainly dark programs and movies the average power power consumption of an identical sized plasma tv is really lower than LCD tv. However if lots of cartoons and sport are viewed then the LCD tv uses less power. Consequently on average with varied viewing content there is little difference between LCD tvs and Plasma tvs. Plasma tv manufacturers are shortly going to be launching models that will cut the power consumption by over half.
Life expectancy
Plasma tv manufacturers are nowadays quoting statistics of 100000 hours for the life expectancy. This represents a usage level of almost 11.5 years of non stop use. Thus any concerns concerning the life expectancy of plasma tvs being less than LCD tvs are unfounded.
Conclusion
Both technologies have benefits. Plasmas tvs typically have a better subjective picture with better black level, higher contrast, and superior colour rendering than LCD TVs. While LCD TVs have higher brightness, freedom from screen burn-in worries, and are lighter and thinner. This is not always the case becausea good LCD TV could have a better picture than an middling or poor plasma TV. Nevertheless on balance I consider that a plasma tv is the superior option with extra advantages. In the end you get what you pay for so spend as much as you can find the money for on you preferred format.
For more information go to Discount LCD TV and Discount Plasma TV
What is HD Ready and HD TV ?
What is HDTV ?
HD TV, where the HD is for high definition television (or high def tvs). This is possibly the most significant revolution in broadcasting since Television changed to colour from black & white. HDTV uses widescreen digital flat panel televisions such as a Plasma televisions and LCD tv's where the screen resolution is at least 1280 pixels x 720 pixels or HD Ready. There are 2 types of high def broadcasting, 720p/50 and 1080i/25.
What does ‘HD ready’ mean ?
If a flat panel television carries the HD Ready label it will work with a HD signal and will be able to display a HD picture. tvs that are specified to meet the requirements of the HD Ready logo must have a minimum picture resolution of (1280 pixels x 720 pixels) i.e. 720 vertical lines in 16:9 widescreen, where the signal received is either 720p/50 or 1080i/25 image formats and to be capable of accepting HD - the ‘50’ or ‘25’ is the amount of frames per second. They must also able to accept HD inputs by either DVI or HDMI and on Component Inputs.
For a 1366 pixels x 768 pixels HD ready TV, if it receives a 1080i signal then scalers within the flat panel tv will down convert the image to fit the 768 lines on a flat screen television. This is done using complex algorithm sequences in the scaler which systematically crops the image down to the resolution of the screen. If the signal is at 720p then the signal will be slightly upscaled to fill the 768 vertical lines using complicated algorithms.
Most HD ready televisions don't have enough pixels to give true pixel-for-pixel mapping without interpolation of the higher HD resolution (1920 pixels x 1080 pixels).
What does ‘HD ready 1080P’ mean ?
Any TV that carries the ‘HD ready 1080p’ is naturally capable of displaying a ‘full’ 1080P signal with sufficient pixels to offer true pixel-for-pixel mapping with no interpolation. A HD ready 1080p flat screen tv has a picture resolution of (1920 pixels x1080 pixels) i.e. 1080P, where ‘1080’ is the vertical resolution of the picture and the ‘P’ is for Progressive scan. HD ready 1080P is the maximum resolution available in the UK on HD televisions hence the ‘full’ term. These sets will display 1080p and 1080i video without distortion i.e. with 1:1 pixel mapping. They also boast HDMI or DVI HD input at 1080p HD and display signals that are at either 24 or 50 frames per second.
If a flat screen 1080P TV receives a 720P picture the signal is ‘oversampled’ to fit the resolution of the 1080P widescreen TV. This is completed using extremely complex algorithm sequences.
Full HD
Older full HD flat panel tv’s may not fulfill all ‘HD Ready 1080P’ requirements.
Interlaced or Progressive
An Interlaced Image involves arranging the scan lines of one frame into two fields where one field contains the odd lines and an additional field contains all of the even lines – so every field has half the resolution. The two fields of the frame are alternately displayed in sequence at a rate that is double the actual frame rate, this is known as Interlacing.
One of the advantages of Interlacing is that when footage is shot of a moving picture each of the fields of a frame are taken at separate times making movements that appears more fluid. Picture Interlacing is a procedure that was originally used to improve the image quality of a signal on CRT tvs without using extra signal bandwidth.
TVs in the UK have a PAL picture system that have a rate of 25 frames per second or 50 fields per second. An Interlaced signal uses half the bandwidth of a Progressive signal i.e. the progressive scanning process has to scan the picture 50 times per second whilst the interlaced scanning process operates at half of that speed.
Standard definition LCD televisions and Plasma televisions displays aren’t able to operate on an interlaced mode for footage shot with a TV or video camera. Because LCD tv displays and Plasma tv displays do not have an electron scan to create an image they cannot benefit from interlacing. So internal processing in the flat panel tv creates a progressive scan image from the interlaced signal.
Progressive Scanning
This is also known as non-interlaced scanning. It is a method of storing, displaying or transmitting a moving picture where all of the lines of every frame are shown sequentially rather than odd lines in one field and then even lines in the subsequent field as per Interlaced signals.
Progressive scan has the benefit of higher vertical resolution than interlaced images with the same frame rate and no interlace artifacts or blurring, and hence less eye strain. Also better results are possible for scaling to higher resolutions than the equivalent interlaced sources. For the best scaling results full frames work the best but interlaced video sources have to be deinterlaced prior to being scaled and this can produce very noticeable combing artifacts.
What is the difference between the 720p/50 and 1080i/25 formats?
A 1080i/25 (1,920x1080 pixel resolution) interlaced signal has to some extent better horizontal resolution on still pictures than a progressive scanned 720p/50 (1,280x720 pixel resolution) image. However on interlaced moving pictures there are inter line twitters which reduce the subjective vertical resolution. The twitter is caused by the frames being slightly different. Both 720p/50 and 1080i/25 are used by broadcasters depending on their inclination and bandwidth availability.
Progressive scanning 720p gives more fluid motion, especially on slow-motion, than an interlaced 1080i signal. But interlaced 1080i signals give better static resolution. If the internal processing is good enough a 1080i signal on a 1080 display will still look better than the 720p material. The best one depends on whether you are to display more static pictures or more moving pictures and what is more critical to you.
It is easier to convert a progressive signal (i.e. 1080p/50) into an interlaced format, such as 1080i/25, than it is to convert an interlaced format into a progressive format.
What is 1080p/24 ?
This is 1080p at 24 frames per second. This gives the greatest picture quality with the 1080p picture decoded directly from the BlueRay disc at 24 frames per second, and then sent to the flat screen HD TV. The 24 frames per second is the same rate as the original cinema film. The Television will then create additional frames to multiply to either 48 or 72 frames per second creating middle frames that make the picture more fluid.
Sources of HDTV
HDTV broadcasts are presently at 720p/50 or 1080i/25 and are available on SKY Digital HD, Freesat, BT Vision, and Virgin media Cable. All of these require a HD Ready TV. At this time Full HD 1080P signals are only obtainable on Blue-Ray Disc, Playstation 3 and by download films on the web. The Xbox 360 games machine operates at 720p.
Conclusion
The additional sharpness and vividness of a high definition television picture enhances the viewing experience. Unless you own, or intend to purchase a Blueray player, Playstation 3 or you are going to down load 1080p HD films off the internet a HD Ready TV will be good enough. The only drawback with this is that if any broadcaster decides to start transmitting in high definition in the near future your purchase wont be able to take full advantage of the added screen resolution. Thus if you want to cover every chance then purchase a full 1080p HD television.
For more details gott HD TV and HD Ready Tv
HD TV, where the HD is for high definition television (or high def tvs). This is possibly the most significant revolution in broadcasting since Television changed to colour from black & white. HDTV uses widescreen digital flat panel televisions such as a Plasma televisions and LCD tv's where the screen resolution is at least 1280 pixels x 720 pixels or HD Ready. There are 2 types of high def broadcasting, 720p/50 and 1080i/25.
What does ‘HD ready’ mean ?
If a flat panel television carries the HD Ready label it will work with a HD signal and will be able to display a HD picture. tvs that are specified to meet the requirements of the HD Ready logo must have a minimum picture resolution of (1280 pixels x 720 pixels) i.e. 720 vertical lines in 16:9 widescreen, where the signal received is either 720p/50 or 1080i/25 image formats and to be capable of accepting HD - the ‘50’ or ‘25’ is the amount of frames per second. They must also able to accept HD inputs by either DVI or HDMI and on Component Inputs.
For a 1366 pixels x 768 pixels HD ready TV, if it receives a 1080i signal then scalers within the flat panel tv will down convert the image to fit the 768 lines on a flat screen television. This is done using complex algorithm sequences in the scaler which systematically crops the image down to the resolution of the screen. If the signal is at 720p then the signal will be slightly upscaled to fill the 768 vertical lines using complicated algorithms.
Most HD ready televisions don't have enough pixels to give true pixel-for-pixel mapping without interpolation of the higher HD resolution (1920 pixels x 1080 pixels).
What does ‘HD ready 1080P’ mean ?
Any TV that carries the ‘HD ready 1080p’ is naturally capable of displaying a ‘full’ 1080P signal with sufficient pixels to offer true pixel-for-pixel mapping with no interpolation. A HD ready 1080p flat screen tv has a picture resolution of (1920 pixels x1080 pixels) i.e. 1080P, where ‘1080’ is the vertical resolution of the picture and the ‘P’ is for Progressive scan. HD ready 1080P is the maximum resolution available in the UK on HD televisions hence the ‘full’ term. These sets will display 1080p and 1080i video without distortion i.e. with 1:1 pixel mapping. They also boast HDMI or DVI HD input at 1080p HD and display signals that are at either 24 or 50 frames per second.
If a flat screen 1080P TV receives a 720P picture the signal is ‘oversampled’ to fit the resolution of the 1080P widescreen TV. This is completed using extremely complex algorithm sequences.
Full HD
Older full HD flat panel tv’s may not fulfill all ‘HD Ready 1080P’ requirements.
Interlaced or Progressive
An Interlaced Image involves arranging the scan lines of one frame into two fields where one field contains the odd lines and an additional field contains all of the even lines – so every field has half the resolution. The two fields of the frame are alternately displayed in sequence at a rate that is double the actual frame rate, this is known as Interlacing.
One of the advantages of Interlacing is that when footage is shot of a moving picture each of the fields of a frame are taken at separate times making movements that appears more fluid. Picture Interlacing is a procedure that was originally used to improve the image quality of a signal on CRT tvs without using extra signal bandwidth.
TVs in the UK have a PAL picture system that have a rate of 25 frames per second or 50 fields per second. An Interlaced signal uses half the bandwidth of a Progressive signal i.e. the progressive scanning process has to scan the picture 50 times per second whilst the interlaced scanning process operates at half of that speed.
Standard definition LCD televisions and Plasma televisions displays aren’t able to operate on an interlaced mode for footage shot with a TV or video camera. Because LCD tv displays and Plasma tv displays do not have an electron scan to create an image they cannot benefit from interlacing. So internal processing in the flat panel tv creates a progressive scan image from the interlaced signal.
Progressive Scanning
This is also known as non-interlaced scanning. It is a method of storing, displaying or transmitting a moving picture where all of the lines of every frame are shown sequentially rather than odd lines in one field and then even lines in the subsequent field as per Interlaced signals.
Progressive scan has the benefit of higher vertical resolution than interlaced images with the same frame rate and no interlace artifacts or blurring, and hence less eye strain. Also better results are possible for scaling to higher resolutions than the equivalent interlaced sources. For the best scaling results full frames work the best but interlaced video sources have to be deinterlaced prior to being scaled and this can produce very noticeable combing artifacts.
What is the difference between the 720p/50 and 1080i/25 formats?
A 1080i/25 (1,920x1080 pixel resolution) interlaced signal has to some extent better horizontal resolution on still pictures than a progressive scanned 720p/50 (1,280x720 pixel resolution) image. However on interlaced moving pictures there are inter line twitters which reduce the subjective vertical resolution. The twitter is caused by the frames being slightly different. Both 720p/50 and 1080i/25 are used by broadcasters depending on their inclination and bandwidth availability.
Progressive scanning 720p gives more fluid motion, especially on slow-motion, than an interlaced 1080i signal. But interlaced 1080i signals give better static resolution. If the internal processing is good enough a 1080i signal on a 1080 display will still look better than the 720p material. The best one depends on whether you are to display more static pictures or more moving pictures and what is more critical to you.
It is easier to convert a progressive signal (i.e. 1080p/50) into an interlaced format, such as 1080i/25, than it is to convert an interlaced format into a progressive format.
What is 1080p/24 ?
This is 1080p at 24 frames per second. This gives the greatest picture quality with the 1080p picture decoded directly from the BlueRay disc at 24 frames per second, and then sent to the flat screen HD TV. The 24 frames per second is the same rate as the original cinema film. The Television will then create additional frames to multiply to either 48 or 72 frames per second creating middle frames that make the picture more fluid.
Sources of HDTV
HDTV broadcasts are presently at 720p/50 or 1080i/25 and are available on SKY Digital HD, Freesat, BT Vision, and Virgin media Cable. All of these require a HD Ready TV. At this time Full HD 1080P signals are only obtainable on Blue-Ray Disc, Playstation 3 and by download films on the web. The Xbox 360 games machine operates at 720p.
Conclusion
The additional sharpness and vividness of a high definition television picture enhances the viewing experience. Unless you own, or intend to purchase a Blueray player, Playstation 3 or you are going to down load 1080p HD films off the internet a HD Ready TV will be good enough. The only drawback with this is that if any broadcaster decides to start transmitting in high definition in the near future your purchase wont be able to take full advantage of the added screen resolution. Thus if you want to cover every chance then purchase a full 1080p HD television.
For more details gott HD TV and HD Ready Tv
Saturday 15 November 2008
100hz LCD tv or 100hz Plasma ?
A standard PAL television will refresh the picture at a frequency of 50Hz – 50 Frames Per Second (FPS). The Frames Per Second are the number of frames needed to create the illusion of movement. Our eyes are at times sensitive to this frequency depending on the speed of the image, the level of darkness, and the level of brightness so you will sometimes notice the picture flicker on a 50Hz TV. Also the larger the screen is the more noticeable the flicker is.
A 100hz (100 FPS) television operates at double the Frames Per Second by creating a replica of each frame and inserting it after the one before. On a 50Hz Cathode Ray Television (CRT) because the picture was produced by an electron scan there was a visible flicker that could be detected by the human eye. By doubling the scan frequency to 100Hz and inserting a replica frame this effect was eliminated as far the eye perceived it. The effect of this is to significantly reduce the flicker.
LCD and Plasma televisions don’t produce flickering because they don’t produce the picture with an electron scan. However LCD TV’s still benefit from 100Hz because advanced digital circuitry creates an extra frame or middle image. This is done by the TV inventing an extra frame using complex interpolation and motion compensation calculations to work out what the extra fields and frames look like rather than inserting a replica frame. (e.g.: the second frame is not the same as the first frame).
However even at 100Hz picture still does not produce a completely smooth picture especially with fast motion images. Some television manufactures attempt to reduce this further by using digital picture processing. In reality there is still some blurring on fast moving images but the benefits are clearer and better-defined surfaces, sharper pictures, and smoother movement than you get from 50Hz LCD screens.
For example if a football moves ten pixels from right to left between frames one, two and three, the 100Hz television will digitally generate two additional frames between one and two, and two and three, in which the ball will move five pixels. This results in five frames in which football moves a total of ten pixels i.e. the original frames one, two and three plus the digitally created frames inserted between one and two, and between two and three. The effect of this is that the eye sees an image that moves more smoothly than before.
The benefit is that 100Hz televisions have a clear benefit of ending a lot of the ghosting effects sometimes seen in LCD TV’s. The ghosting effect caused by the new image being displayed before the previous has faded away. Click the following link for more information and to Save Pounds on Lcd and Plamsa Tv's at Low Prices
Sony has just launched a 200Hz range which digitally inserts three additional frames between the original 50Hz frames. The effect of this is that fast moving sequences are delivered with a smoother, more fluid and sharper picture than 50Hz or even 100Hz TV’s.
Most leading manufactures have now got 100Hz LCD and Plasma televisions including Panasonic, JVC, Samsung, Toshiba, Sony, Philips, LG, Pioneer, and Hitachi. For further advice and discount pricing Buy LCD or Plasma at Discount Prices
Studies have shown that 100Hz televisions can help prevent seizures in patients with photosensitive epilepsies when viewing television or playing video games.
A 100hz (100 FPS) television operates at double the Frames Per Second by creating a replica of each frame and inserting it after the one before. On a 50Hz Cathode Ray Television (CRT) because the picture was produced by an electron scan there was a visible flicker that could be detected by the human eye. By doubling the scan frequency to 100Hz and inserting a replica frame this effect was eliminated as far the eye perceived it. The effect of this is to significantly reduce the flicker.
LCD and Plasma televisions don’t produce flickering because they don’t produce the picture with an electron scan. However LCD TV’s still benefit from 100Hz because advanced digital circuitry creates an extra frame or middle image. This is done by the TV inventing an extra frame using complex interpolation and motion compensation calculations to work out what the extra fields and frames look like rather than inserting a replica frame. (e.g.: the second frame is not the same as the first frame).
However even at 100Hz picture still does not produce a completely smooth picture especially with fast motion images. Some television manufactures attempt to reduce this further by using digital picture processing. In reality there is still some blurring on fast moving images but the benefits are clearer and better-defined surfaces, sharper pictures, and smoother movement than you get from 50Hz LCD screens.
For example if a football moves ten pixels from right to left between frames one, two and three, the 100Hz television will digitally generate two additional frames between one and two, and two and three, in which the ball will move five pixels. This results in five frames in which football moves a total of ten pixels i.e. the original frames one, two and three plus the digitally created frames inserted between one and two, and between two and three. The effect of this is that the eye sees an image that moves more smoothly than before.
The benefit is that 100Hz televisions have a clear benefit of ending a lot of the ghosting effects sometimes seen in LCD TV’s. The ghosting effect caused by the new image being displayed before the previous has faded away. Click the following link for more information and to Save Pounds on Lcd and Plamsa Tv's at Low Prices
Sony has just launched a 200Hz range which digitally inserts three additional frames between the original 50Hz frames. The effect of this is that fast moving sequences are delivered with a smoother, more fluid and sharper picture than 50Hz or even 100Hz TV’s.
Most leading manufactures have now got 100Hz LCD and Plasma televisions including Panasonic, JVC, Samsung, Toshiba, Sony, Philips, LG, Pioneer, and Hitachi. For further advice and discount pricing Buy LCD or Plasma at Discount Prices
Studies have shown that 100Hz televisions can help prevent seizures in patients with photosensitive epilepsies when viewing television or playing video games.
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