High Definition TV or HDTV is the biggest change to broadcasting and television since the introduction of colour. Flat panel lcd televisions and plasma televisions with a minimum screen resolution of 1280 x 720 pixels are known as HD Ready and are capable of displaying current HD broadcasts.
What does 'HD ready' mean ?
Any television that is HD Ready is capable of receiving and displaying a HD picture. To meet this specification the TV should have a picture resolution of at least 1280 x 720 pixels. They have to be able to receive a signal that is 1080i/25 or 720p/50, where the 1080 or 720 is the number of vertical lines, the 'i' is for an interlaced picture and the 'p' is for a progressive scan picture, and the 25 and the 50 are the number of frames displayed each second. In addition the televisions must have either DVI or HDMI and Component signal input connectors.
For a 1366 pixels x 768 pixels HD ready TV, if it receives a 1080i signal then scalers inside the flat screen tv will down convert the image to fit the 768 lines flat panel television. This is done using complex algorithm sequences in the scaler which systematically crops the picture down to the resolution of the screen. If the signal is at 720p it follows that the signal will be slightly upscaled to fill the 768 vertical lines with complicated algorithms.
If a HD Ready tv receives a full HD signal of resolution 1920 X pixels 1080 pixels the picture signal has to be interpolated or converted down to display the image. One to one mapping of the pixels is not doable.
'HD Ready 1080p' - What is it ?
If a plasma television or lcd tv has a 'HD ready 1080p' badge it has an adequate amount of pixels to display the full 1080p signal with pixel for pixel mapping with no interpolation. A 1080p flat screen lcd television or plasma television is 1920 x pixels 1080 pixels where the 1080 is the vertical resolution and the 'p' is for progressive scan. A HD Ready 1080p widescreen lcd television or plasma tv is the highest picture resolution in the UK for high definition and therefore the term 'full'. Any plasma television or lcd television with this resolution can show 1080i and 1080p signals with no up or down scaling, and by way of one to one pixel mapping. Connectivity ought to be by either HDMI or DVI inputs. HD Ready 1080p full hd tvs must be able to display a 1080p/24 or 1080p/50 signal where the 24 and the 50 signify the quantity of frames per second.
If a 720p signal is received by a 1080p television it is oversampled (or upscaled) to fill up the resoltion of the 1080p HD TV by way of advanced software.
Full HD
Before the HD ready 1080P specification was established some flat panel TVs were described as Full HD. These sets may not be compatible with the HD ready 1080P standard and may not display some inputs.
What is an Interlaced or Progressive picture ?
An Interlaced Picture involves arranging the scan lines of one frame into two fields where one field contains the odd lines and another 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 twice as fast as the actual frame rate, this is known as Interlacing.
When a image is interlaced, moving images on video seem to have smoother motion since each field of the frame are shot at different times. The system of picture interlacing was in the first place used to enhance the quality of the picture on CRT tvs using the equivalent amount of bandwidth for the broadcast signal.
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 utilizes half the bandwidth of a Progressive signal i.e. the progressive scanning process needs to scan the picture 50 times per second whilst the interlaced scanning process works at half of that speed.
Interlaced pictures on recordings made for television or with a video camera aren't able to be displayed on normal definition LCD tvs and Plasma tvs. This is because the picture isn't created with an electron scan like CRT tv's so LCD tvs and Plama tvs don't gain from the interlaced picture signal. Flat panel widescreen tv's have internal processing to produce a progressive scanned image from a interlaced picture - i.e. Deinterlacing.
Progressive scan delivers benefits.
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 each frame are shown sequentially instead of odd lines in one field and then even lines in the subsequent field as per Interlaced signals.
The vertical resolution when the frame rate is the same is greater for a progressive image than it is for an interlaced image and the picture is free of interlace artifacts, blurring, and greatly lower eye strain. With a progressive image it can be scaled to a higher resolution than an interlaced image giving a higher quality image. This is due to the deinterlacing that is required on an interlaced image preceding any scaling resulting in combing artifacts that are obvious.
720p/50 and 1080i/25 - What is the difference ?
When a 1080i/25 (1,920 x 1080 pixels resolution) signal displays a still image the horizontal resolution is marginally better than the 720p/50 (1,280 x 720 pixels resolution) picture. When an picture moves on an interlaced signal the subjective line resolution is reduced due to line twitter since the two fields that make up the frames are a little different. Depending on the bandwidth availability broadcasters are now using either 720p/50 or 1080i/25.
A progressively scanned 720p will produce smoother picture movement than a 1080i interlaced signal, especially on slow motion. With good quality internal processing a 1080i appears to come up with a better picture than a 720 signal. The best operating mode will depend on whether the screen is being used more with still images than moving pictures, and on the quality of the internal processing.
The conversion of a progressive source such as 1080p/50 into an interlaced configuration such as 1080i/25 is easier than the conversion of an interlaced signal to a progressive format.
The benefits of a 1080p/24 signal.
Because the films that are shown in cinemas are created at 24 frames per second a signal is in its purest form at this frame rate. Films are obtainable on Blueray disc at 24 frames per second with the purpose of givingthe definitive picture quality when displayed on widescreen full high definition televisions. When a full hd television receives a 1080p/24 signal it creates added middle frames, which are inserted between the original ones to raise the frame rate to 48 or 72 frames per second giving more fluid motion.
HDTV Sources
A HD Ready tv can receive all current broadcast formats of 720p/50 or 1080i/25. HD is available on Freesat, Sky Digital HD, BT Vision, and Virgin media cable. The only sources of Full HD 1080P signals are Blueray players, Playstation 3 and by download on the internet. The games on an Xbox 360 are at 720P.
In conclusion
High definition television produces an enhanced subjective picture quality that makes the argument for HD compelling. If you have possession of, or plan to own, a Playstation 3, a Blueray player, or download full HD films from the internet it follows that a Full HD 1080p television is the best option. If not a HD Ready television will be appropriate. Whilst these recommendations deal with today's available options they don't allow for the chance of forthcoming broadcasts in Full 1080p HD. If you would like to be totally sure that you protect your purchase against this scenario then buy a Full 1080p HD flat screen television. - 16732
What does 'HD ready' mean ?
Any television that is HD Ready is capable of receiving and displaying a HD picture. To meet this specification the TV should have a picture resolution of at least 1280 x 720 pixels. They have to be able to receive a signal that is 1080i/25 or 720p/50, where the 1080 or 720 is the number of vertical lines, the 'i' is for an interlaced picture and the 'p' is for a progressive scan picture, and the 25 and the 50 are the number of frames displayed each second. In addition the televisions must have either DVI or HDMI and Component signal input connectors.
For a 1366 pixels x 768 pixels HD ready TV, if it receives a 1080i signal then scalers inside the flat screen tv will down convert the image to fit the 768 lines flat panel television. This is done using complex algorithm sequences in the scaler which systematically crops the picture down to the resolution of the screen. If the signal is at 720p it follows that the signal will be slightly upscaled to fill the 768 vertical lines with complicated algorithms.
If a HD Ready tv receives a full HD signal of resolution 1920 X pixels 1080 pixels the picture signal has to be interpolated or converted down to display the image. One to one mapping of the pixels is not doable.
'HD Ready 1080p' - What is it ?
If a plasma television or lcd tv has a 'HD ready 1080p' badge it has an adequate amount of pixels to display the full 1080p signal with pixel for pixel mapping with no interpolation. A 1080p flat screen lcd television or plasma television is 1920 x pixels 1080 pixels where the 1080 is the vertical resolution and the 'p' is for progressive scan. A HD Ready 1080p widescreen lcd television or plasma tv is the highest picture resolution in the UK for high definition and therefore the term 'full'. Any plasma television or lcd television with this resolution can show 1080i and 1080p signals with no up or down scaling, and by way of one to one pixel mapping. Connectivity ought to be by either HDMI or DVI inputs. HD Ready 1080p full hd tvs must be able to display a 1080p/24 or 1080p/50 signal where the 24 and the 50 signify the quantity of frames per second.
If a 720p signal is received by a 1080p television it is oversampled (or upscaled) to fill up the resoltion of the 1080p HD TV by way of advanced software.
Full HD
Before the HD ready 1080P specification was established some flat panel TVs were described as Full HD. These sets may not be compatible with the HD ready 1080P standard and may not display some inputs.
What is an Interlaced or Progressive picture ?
An Interlaced Picture involves arranging the scan lines of one frame into two fields where one field contains the odd lines and another 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 twice as fast as the actual frame rate, this is known as Interlacing.
When a image is interlaced, moving images on video seem to have smoother motion since each field of the frame are shot at different times. The system of picture interlacing was in the first place used to enhance the quality of the picture on CRT tvs using the equivalent amount of bandwidth for the broadcast signal.
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 utilizes half the bandwidth of a Progressive signal i.e. the progressive scanning process needs to scan the picture 50 times per second whilst the interlaced scanning process works at half of that speed.
Interlaced pictures on recordings made for television or with a video camera aren't able to be displayed on normal definition LCD tvs and Plasma tvs. This is because the picture isn't created with an electron scan like CRT tv's so LCD tvs and Plama tvs don't gain from the interlaced picture signal. Flat panel widescreen tv's have internal processing to produce a progressive scanned image from a interlaced picture - i.e. Deinterlacing.
Progressive scan delivers benefits.
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 each frame are shown sequentially instead of odd lines in one field and then even lines in the subsequent field as per Interlaced signals.
The vertical resolution when the frame rate is the same is greater for a progressive image than it is for an interlaced image and the picture is free of interlace artifacts, blurring, and greatly lower eye strain. With a progressive image it can be scaled to a higher resolution than an interlaced image giving a higher quality image. This is due to the deinterlacing that is required on an interlaced image preceding any scaling resulting in combing artifacts that are obvious.
720p/50 and 1080i/25 - What is the difference ?
When a 1080i/25 (1,920 x 1080 pixels resolution) signal displays a still image the horizontal resolution is marginally better than the 720p/50 (1,280 x 720 pixels resolution) picture. When an picture moves on an interlaced signal the subjective line resolution is reduced due to line twitter since the two fields that make up the frames are a little different. Depending on the bandwidth availability broadcasters are now using either 720p/50 or 1080i/25.
A progressively scanned 720p will produce smoother picture movement than a 1080i interlaced signal, especially on slow motion. With good quality internal processing a 1080i appears to come up with a better picture than a 720 signal. The best operating mode will depend on whether the screen is being used more with still images than moving pictures, and on the quality of the internal processing.
The conversion of a progressive source such as 1080p/50 into an interlaced configuration such as 1080i/25 is easier than the conversion of an interlaced signal to a progressive format.
The benefits of a 1080p/24 signal.
Because the films that are shown in cinemas are created at 24 frames per second a signal is in its purest form at this frame rate. Films are obtainable on Blueray disc at 24 frames per second with the purpose of givingthe definitive picture quality when displayed on widescreen full high definition televisions. When a full hd television receives a 1080p/24 signal it creates added middle frames, which are inserted between the original ones to raise the frame rate to 48 or 72 frames per second giving more fluid motion.
HDTV Sources
A HD Ready tv can receive all current broadcast formats of 720p/50 or 1080i/25. HD is available on Freesat, Sky Digital HD, BT Vision, and Virgin media cable. The only sources of Full HD 1080P signals are Blueray players, Playstation 3 and by download on the internet. The games on an Xbox 360 are at 720P.
In conclusion
High definition television produces an enhanced subjective picture quality that makes the argument for HD compelling. If you have possession of, or plan to own, a Playstation 3, a Blueray player, or download full HD films from the internet it follows that a Full HD 1080p television is the best option. If not a HD Ready television will be appropriate. Whilst these recommendations deal with today's available options they don't allow for the chance of forthcoming broadcasts in Full 1080p HD. If you would like to be totally sure that you protect your purchase against this scenario then buy a Full 1080p HD flat screen television. - 16732
About the Author:
Armadeus Cornelius has almost 2 decades experience in the electrical sector. To find out more contact his web site for more information about HD TV. Alternatively you can visit his on-line electrical store for LCD HD TV & Plamsa HD TV Discounts.
