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Old 14th August 2005, 23:37   #20  |  Link
CiNcH
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Join Date: Jan 2004
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Here's my interpretation of Psychovisual Modeling / Psychovisual Heuristics:

Psychovisual modeling algorithms exploit the peculiarities of the Human Visual System (HVS). This knowledge allows the encoder to more efficiently allocate video data, helping it to increase perceptual quality. This area is full of possibilities which are continuously being explored and developed.

On FrameLevel data is reduced for a video sequence at full frame rate in a way that the HVS does not notice.

On MacroblockLevel distortions are masked in dark/bright (luminance masking) or highly textured areas of the picture (in other words bit spend is reduced) where the HVS does not notice it, details in flat areas, where the human eye is most sensitive, are enhanced.

Although psychovisual heuristics appear to improve quality the PSNR score drops, so the PSNR metric does not have a good correlation with subjective perception of video quality.


Psy-Vis in latest Ateme AVC Encoder Beta (I am not a tester so I am not aware of its effects)

Quote:
There are 4 psychovisual levels, which are independant from the other settings.

* psy 0 -> no psychovisual heuristics
* psy 1 -> psychovisual heuristics on a frame level
* psy 2 -> psychovisual heuristics on a macroblock level
* psy 3 -> enhanced psychovisual heuristics on a macroblock level. Some people prefer it over psy 2, others don't.
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Last edited by CiNcH; 14th August 2005 at 23:51.
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