From this month all new Bang & Olufsen BeoVision 7-40 models are being manufactured with 200Hz refresh rates. But what exactly does this mean?
Before 200Hz came both 100Hz and 50Hz
To begin with, ordinary PAL cathode ray televisions (CRTs) created a viewed picture which was made up of fifty separate images (frames per second or FPS) which our brains subsequently slotted together in order to create a perceived moving image. In the US and other countries around the world where 60Hz electricity was standard, this ‘refresh rate’ was sixty times a second.
FPS are the number of frames necessary to create the illusion of flowing movement. Human perception - through the interface of our eyes and brains - is very conscious of image ‘movement’, the depth of dark areas and picture brightness. Because of former relatively low level refresh rates the viewer would on occasion experience image flicker, especially during action scenes. And the bigger the image being viewed, the greater this apparent flicker. This became particularly acute on larger LCD and plasma televisions.
At 100 FPS (100Hz), television works at twice the standard frames per second by producing a digitally-created double image of each frame, inserting it subsequent to the previous one. By creating a picture from twice the number of images (100 instead of 50) the flicker became less apparent.
Benefits of 100Hz screens
Plasma and LCD TVs do not have the same problem as CRTs as they do not produce images the same way. Nevertheless LCD TVs - along with Plasma televisions - still gain from 100 Hertz because innovative digital circuitries within the televisions create an extra frame or middle image. The television does this by using frame interpolation, as well as motion compensation which calculates how addition fields and frames should appear, as an alternative of putting in a second frame (e.g. the first and second frames are different).
Yet, even at 100Hz the figure still does not make an entirely smooth picture - especially with faster movement images. Television manufacturers aim to decrease this even further by proprietary digital processing. However, the result is still a little blurring and flickering on quick-moving images even though the refresh rates have been doubled.
In sports’ scenes for example, if a football moves ten pixels from left to right between frames one, two and three, a 100Hz television would digitally make up two extra frames between images one and two, and two and three, whereby the football would make up five pixels. The result of this is that the brain perceives more of a consistency in the way the ball moves, and with less flicker or image judder.
The world’s TV manufacturers realised the benefits of watching faster-moving scenes through digitally enhancing screen images through onboard digital processing and this advancement has been improved even further with yet another doubling of refresh rates recently, with the introduction of 200Hz processing.
It’s getting better all the time…
By inserting digitally-produced interpolation frames between TV frames and displaying 200Hz, animation blur is yet further reduced, with more natural and smoother animation being created by ‘intelligently’ calculating motion movements within the TV set itself.
Studies have also determined that 100Hz and 200Hz TVs can aid individuals who experience photosensitive epilepsies when watching television or playing computer games.
BeoVision 7-40 joins the BeoVision 10 with its 200Hz technology.