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An Introduction to 50hz tv pictures

Ordinarily PAL televisions will refresh the picture with a frequency of 50 Frames Per Second (FPS).The Frames Per Second (FPS) are the number of frames required to generate the illusion of motion. On a 50 FPS (50Hz) Cathode Ray Television (CRT), due to the picture being produced with an electron scan, there is a visible flicker that is seen by the human eye.

Our eyes are at times are 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.

Early 100 hertz technology

A 100 hz TV operates at twice the Frames Per Second (100FPS) by producing a replica of every frame and inserting it after the previous one. The result of this doubling of the scan frequency to 100Hz and inserting a copy frame is that this problem was eliminated as far as the eye perceived it. The result of this is to significantly lower the flicker.

How does 100hz work on LCD and Plasma Tv ?

Plasma and LCD televisions dont produce flicker since they dont generate the picture with a scan. LCD TVs still benefit from 100FPS because sophisticated digital circuitry creates an additional frame or middle image. This is done by the TV creating an extra frame by means of complex motion compensation as well as interpolation calculations to calculate what the extra fields and frames look like rather than inserting a duplicate frame. (i.e. the first and second frames are different).

However even at 100 FPS the picture still does not deliver a entirely smooth picture particularly with fast motion images. Some television manufactures attempt to reduce this further by employing digital picture processing. Typically there is still a little blurring on quick moving images but the benefits are clearer and better-defined surfaces, sharper pictures, and smoother movement than is possible from 50 Frames Per Second Plasma and LCD televisions.

e.g. For a football that travels ten pixels from left to right between frames one, two and three, the 100 hertz TV will digitally create two further frames between one and two, and two and three, between which the ball will move five pixels. This will result in five frames where the 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 in between two and three. The result of this is that the eye sees an image that moves smoother than before.

100 hz is a benefit

100Hz televisions have the clear benefit of eliminating a lot of the ghosting effects occasionally seen in LCD TVs. Ghosting effects caused by the next image being shown before the earlier one has faded away. Even on Plasma tv the creation of the middle frame results in a more fluid picture

Manufacturers such as JVC, Panasonic, Samsung, Toshiba, LG, Sony, Philips, Hitachi and Pioneer have got 100 hertz Plasma and LCD televisions.

200hz is even better

A new series of 200 hertz televisions have been launched by Sony which digitally inserts three additional frames between the original 50 hertz frames. Thus fast moving sequences are delivered with a smoother, more fluid and sharper picture than 50Hz or even 100 hertz TV's.

Additional benefit for photosensitive epilepsy sufferers

Research has proven that 100 hertz televisions can assist in preventing seizures in people who suffer with photosensitive epilepsies when viewing television or playing computer games.