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