As high definition display hardware becomes more common, users are becoming increasingly aware of the performance characteristics inherent in the design of fixed pixel displays. Many factors affect the quality of the displayed image, including encoding quality of digital source material, quality of source equipment and cabling, poor equipment earthing and dirty mains supply.

All high definition displays need to process the source material in a number of ways to generate the image seen on screen. Some high definition screens are undoubtedly much better than others at dealing with all types of source material and so we felt it would be useful to explain how plasma technology handles the video signals and explain just why these displays are better.

A number of characteristics have been reported recently and have been interpreted as faults in the display device however most of these are inherent in the design of plasma technology and should not be an issue in day to day use.

We hope the below document with be of interest and provide some background to help understand the many complex factors that go together to create a great image on the display.

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However, the symptom is quite common on certain channels broadcast via terrestrial, satellite, or cable television. This arises when the broadcast itself is sent out of sync in the first place (see Sky Sports News for some of the worst!) and as such can increase the delay time to around 80 milliseconds, which is more noticeable – including on large screen normal TVs.

For those of you who have introduced a dedicated video processor into your system, this may exaggerate the problem further. Many AV amps now include audio delay functions to combat this, and we have found an analogue audio effects box that can also be used.

Plasmas and flatpanel screens are also affected by this characteristic. Due to the technological constraints of building an LCD chip, or pixel based technology, manufacturers can only guarantee that approximately 99.9% of pixels will be functional. The actual number of allowable failures varies from manufacturer to manufacturer and from product to product.

A pixel can be stuck open (brite white dot), stuck closed (no output) or stuck on red, green or blue. Many manufacturers place a different weighting on different types of pixel defect e.g. a projector with 2 blue pixels and a black one may still be within specification and as such not-faulty, whereas that same projector with just two white pixels may be outside of specification and therefore warrants a replacement.

Defective pixels cannot be repaired (although strangely enough some have been known to pop back into life!!!

To a degree the scaling/deinterlacing/progressive scan in the display will improve on this – better displays will make a better job of it. You can also opt for a dedicated video processor to improve the picture further.