View source for PSNR

'''PSNR''' stands for '''P'''eak '''S'''ignal-to-'''N'''oise '''R'''atio. It is used as a measure of [http://en.wikipedia.org/wiki/Video_quality video quality]. It is expressed in [[wikipedia:Decibel|decibels]]. It's defined as
[[File:PSNR_Eq1.png|x48px|<math>PSNR(I,K) = 20 \cdot \log_{10}{(\frac{255}{\sqrt{MSE(I,K)}})}</math>]]

where ''{{Serif|I}} ''is the reference image, ''{{Serif|K}} ''is the image under test, and ''{{Serif|MSE}} ''is the [http://en.wikipedia.org/wiki/Mean_squared_error Mean Squared Error] between the two:

[[File:PSNR_Eq2.png|x48px|<math>MSE(I,K) = \frac{1}{M} \cdot \sum_{j=0}^{width-1} \sum_{k=0}^{height-1} &#124; I(j,k) - K(j,k) &#124;^{2}</math>]]

The double-{{Serif|Σ}} term states that {{Serif|(''j'',''k'')}} runs over all pixels of the frame, summing the squared absolute value of the difference between reference image {{Serif|''I''}} and test image {{Serif|''K''}}.

'''External Links'''
* For more details see [http://en.wikipedia.org/wiki/PSNR wikipedia:PSNR].
* See also, [http://en.wikipedia.org/wiki/Structural_similarity wikipedia:SSIM] (Structural SIMilarity), another widely-used quality measure.
* See also, [http://en.wikipedia.org/wiki/Video_quality wikipedia:Video Quality] for a discussion of the difficulties involved in trying to make an "objective" quality measurement.

[[Category:Glossary]]