[theora] [Fwd: psnr/video codecs tests]

[Gabriel Bouvigne]

I am forwarding to the list a mail that I send to one of the 
subscribers, related to codecs comparison.

Perhaps the material will be helpful to some of you.

<p>Regards,

<p>
----
Gabriel Bouvigne
www.mp3-tech.org
personal page: http://gabriel.mp3-tech.org




<strong>attached mail follows:</strong><hr noshade>


Hello

I just looked at your vp3/mp4 comparison.
In this test you used psnr to compute differences between original and 
coded samples.
You mentionned some drawbacks of psnr. I totally agree with the fact 
that a few differences (lets say a small lumi difference) might give a 
very bad psnr.

That is why a few years ago, I made a small tool to bypass those problems.
The tool is a difference comparator for color images. This tool allows 
you to use several test criterions:
*luminance
*chrominance
*local emerging of pixels
*correllation with neighbours
*contour

This tool is limited on the size of input pictures, so you have to crop 
images first.
I think that this tool might be usefull to you.
It is available on gabriel.mp3-tech.org.

I do not have time anymore to work on it (source code is available), but 
if you need some information I can help you.

<p>Regards,

<p>
----
Gabriel Bouvigne
www.mp3-tech.org
personal page: http://gabriel.mp3-tech.org

<p><p>--- >8 ----
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