DrDivx and psychovisual enhancement

[dannyv]

I know you are all going to boo me for using DrDivx but it does work for me.

Can anyone tell me what the setting "psychovisual enhancement" under the pre-processing tab does. The setting choices are off, shapeing and masking. I do a lot of .ts HD stream processing and output the stream to a 1280x720 divx file. I also upconvert standard DVD content to a 1280x720divx file.

So I guess my questions are.

1. What does psychovisual enhancement do.
2. What does each setting do.
3. Would it benefit me to use this setting considering the type of encoding I'm doing?

[Dark Shikari]

While I don't know DivX enough to give you a specific answer, psychovisual enhancement is enhancement that usually decreases objective quality metrics such as SSIM/PSNR but increases visual quality as perceived by humans. One example of a psychovisual enhancement is Adaptive Quantization in x264, which allocates more bits to dark background areas to reduce blocking, which reduces quality metrics but generally helps visual quality.

[dannyv]

While I don't know DivX enough to give you a specific answer, psychovisual enhancement is enhancement that usually decreases objective quality metrics such as SSIM/PSNR but increases visual quality as perceived by humans. One example of a psychovisual enhancement is Adaptive Quantization in x264, which allocates more bits to dark background areas to reduce blocking, which reduces quality metrics but generally helps visual quality.


Thank you for the explination.
If I understand this correctly then. Shapeing i assume would make a sharper image but may more define micro blocking in dark areas. As masking would reduce (mask) the microblocking in dark areas but would reduce the sharpness of the picture.

[jethro]

Thank you for the explination.
If I understand this correctly then. Shapeing i assume would make a sharper image but may more define micro blocking in dark areas. As masking would reduce (mask) the microblocking in dark areas but would reduce the sharpness of the picture.

nonono, I think the above was only an example of psy enhancement and you should not interpret it in any way relating to Divx.
But I would also be interested in finding more information about Divx psy enhancements.:)

[Sharktooth]

maybe some DivX guy may enlighten us.

[Dark Shikari]

nonono, I think the above was only an example of psy enhancement and you should not interpret it in any way relating to Divx.
But I would also be interested in finding more information about Divx psy enhancements.:)Correct, it was just an example of a type of psy enhancement, its not the only type, just a common type.

[delacroixp]

I dredged up a thread on Psychovisual Enhancement (http://forums.divx.com/forum/viewTopic.php?id=540) from the official DivX Forums though it is a little bit dated...
Basically, use shaping for general usage and masking for anime and cartoons...

According to the DivX User Guide 5.2 (http://www.divx.com/divx/windows/codec/guides/).
PE is a technique based on human perception to intelligently lose detail where it is least likely to be noticed before degrading the remainder of the picture. This perceptual technique forms the basis of psychovisual enhancement, letting DivX mask the artifacts inherent in MPEG-4 video in areas of the picture where error is least perceivable.


This is the basis of H264 which automatically uses the limitations of human biology and evolution to package fairly HD movies onto a rather small disk space...
I guess it's the ultimate magic trick of illusion... "ignorance is bliss"...
1 hour of original HD footage can come in at 560 GB... making a lot of shoe-horning necessary to bring it down to a 10 or 20 GB DVD


It should be noted that while all humans are similar... biology and perception will differ... making psychovisual enhancement "trickery" more successfull on certain viewers than others.
Trial and error is probably the best way to discover what works for you...
A good bottle of wine isn't equally appreciated by all.


:):devil::D
Pascal