[opendtv] Re: Image quality

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 15 Nov 2005 09:09:03 -0500

At 2:28 AM +0100 11/13/05, Olivier Houot wrote:
>Albert.e.Manfredi wrote:
>>I've read that optically, the eye per se >is not that
>>great. What makes our vision what it >is is the processing
>>done in that small part of the brain.
>
>But if you consider the visual system as a whole put together eye,
>actuators, and brain processing circuitry, it still outperforms
>modern HDTV cameras for a fraction of the size and weight.
>
>Perhaps we could emulate that with a lightweith sensor , some piezo-
>electric actuators and some processing to stitch together the
>overlapping pictures acquired by optical scanning.
>
>As the eye needs hundreds of milliseconds to build a full UHDTV
>picture, and our bionic counterpart would need to provide one
>complete picture every 1/60 th of a second , it would need to operate
>at least ten times faster, but replacing jelly by steel, plastic,
>quarz and silicium should allow for that.
>

Dr. Bill Glenn, at Florida  Atlantic University built an HDTV camera 
that did some of this. It could capture extra detail in the static 
areas of the image, and less detail in the moving areas of the image. 
But it did not work because of eye tracking, which allows us to focus 
on a portion of the image to acquire high resolution detail. In the 
real world the stimulus is always consistent across the field of 
view. Our visual system decides over what portion of that field to 
acquire a high resolution image.

When we are looking at HDTV the eye can do the same thing as in the 
real world - i.e. we can look for extra detail anywhere in the image, 
so the acquisition system must produce a HD view across the entire 
image field if we want to trick the human visual system into thinking 
it is looking at the real thing.  It is VERY IMPORTANT to note that 
the induction effect - the illusion of reality or immersion- can only 
take place when the HD image covers a large portion of the human 
field of view, so that eye tracking can take place.

This does not happen with SDTV, which covers only a small portion of 
the field of view, or with HDTV on smaller screens that only cover a 
small portion of the field of view.

Regards
Craig
 
 
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