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PSNR stands for Peak Signal-to-Noise Ratio. It is used as a measure of video quality. It is expressed in decibels. It's defined as <math>PSNR(I,K) = 20 \cdot \log_{10}{(\frac{255}{\sqrt{MSE(I,K)}})}</math>

where I is the reference image, K is the image under test, and MSE is the Mean Squared Error between the two:

<math>MSE(I,K) = \frac{1}{M} \cdot \sum_{j=0}^{width-1} \sum_{k=0}^{height-1} | I(j,k) - K(j,k) |^{2}</math>

Where M is the number of pixels in a frame (width · height)

The double-Σ term states that (j,k) runs over all the pixels, summing the square of the difference between reference image I and test image K.

External Links

  • For more details see wikipedia:PSNR.
  • See also, wikipedia:SSIM (Structural SIMilarity), another widely-used quality measure.
  • See also, wikipedia:Video Quality for a discussion of the difficulties involved in trying to make an "objective" quality measurement.
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