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Motion explained

Regarding all these flashy HDTV pictures out there, one very common problem is always neglected although it can't literally be overlooked: still images are good, but as soon as there is any, even the slightest motion, everything gets blurred, and everything that just looked as real as if you could grabit with your hands suddely gets fuzzy, unreal, just like a bad picture, that it actually is.
There are many reasons for this, all having to do with wide spread lack of knowledge about basic facts with visual perception, and inadequate technical concepts resulting thereof.
One major misunderstanding however is the worst of them all, as it affects almost any flatscreen so far:
Consider a small object moving against a background. Inevitably, the eye follows the object. The eye however will do this by a more or less continuous motion. With typical flat panel displays, every single object picture will stay for the entire frame length, but the observer's eye moves continuously during this time, hence the object will get blurred !
The same problem of course affects almost any kind of motion within a picture, or of the entire picture as well.

There are two cures for this:

1) Flash the display illumination, showing each picture just for a short instant. This is what conventional picture tubes do anyway*.

2) Increase the frame rate. But consider that even doubling the frame rate only removes 50% of the blur.

50 frames per second flashing, may cause some flicker if a large screen is viewed at close distance (which mainly happens in the shopping mall), but in terms of crisp motion pictures, this is still way better than even true 100 fps continuous. 100 fps and flashing would be best.

A cheap, simple and good solution would let the display show interlaced lines unchanged, and flash it. This is possible if the display's resolution matches the picture resolution. A display with 1080 lines could easily display 1080i as well as 540i (16:9), just swallowing 36 lines from a low resolution TV picture - still a lot better than the murky signal processing typical for current products.

Of course, this doesn't really help with many of these 'big' motion pictures, shot at archaic 24 frames per second and with long exposure times, blurring motion just intentionally, to cover up the stuttering resulting from the low frame rate. But we aren't dealing with fossile technology here, are we?

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*one of the most popular and sticky misunderstandings about TV technology is that CRT phosphors are designed to emit light for an entire frame length. This is entirely wrong.

 


 



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