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From: hsoj on 13 Dec 2009 14:45
>>On Apr 3, 6:25=A0am, "praveen.264" <kpk_...(a)yahoo.co.in> wrote:
>>> Hi friends !
>>>
>>> Iam trying to project the performance of our video processing
>algorithm
>>> objectively in terms of PSNR and SSIM. We are dealing with YV12
videos.
>I=
>>am
>>> using the MSU Video Quality measurement tool to compute the PSNR and
>SSIM
>>> values. Here they give the options to compute the values for
>Y-componet
>>> alone (and average for all the Y frames), U componet alone (and
average
>f=
>>or
>>> all the U frames),V componet alone (and average for all the V frames.
>>>
>>> My question here is which value should I take into consideration (Y,
U
>or
>>> V?? or the average of Y,U,V values??) for comparing with unprocessed
>vide=
>>o?
>>>
>>> to summarize,
>>>
>>> what will be correct PSNR for a YUV video - =A0Y component PSNR, U
>compon=
>>ent
>>> PSNR or V component PSNR or the average of the three?
>>>
>>> Pls give ur valuable inputs..
>>>
>>> Thanks in advance,
>>> Praveen
>>
>>There is no one answer that is "correct". I have seen much literature
>>in the video compression community where the Y PSNR is the primary
>>metric, and the others are ignored, or assumed to follow fairly
>>closely. If you wanted conservative results, you could use max of
>>Y,U,V. But there's certainly no reason you can't average them either.
>>If on the other hand you're try to compare against some other
>>published literature, you should do exactly what they do to make the
>>comparison more fair.
>>
>> - Kenn
>>
>
>Thanks Kenn for the reply. I have been going through some literatures
for
>reference. I could only find the term "Avg. PSNR" or "MSSIM" but no
where
>clearly mentioned whether it is of Y, U ,V or avg of YUV. Can u pls let
me
>know what the standard practice is ? I am a newbie to this stuff.
>
>Thanks
>
>Praveen
>
>
>

I am doing some reading on SSIM for my DSP course and here is a good start
on SSIM and also the code to calculate.

This is the web page of the originator (to my knowledge) for this
algorithm

http://www.ece.uwaterloo.ca/~z70wang/research/ssim/

and if you scroll through you will find the link to download his
algorithm

http://www.ece.uwaterloo.ca/~z70wang/research/ssim/ssim.m

[SSIM, qMap] = ssim(original_image, comparison_image );

he also has a non reference algorithm that works pretty nice. Its not
perfect though

good luck!


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