pnmpsnr - compute the difference between two images (the
PSNR)
SYNOPSIS
pnmpsnr [pnmfile1] [pnmfile2]
DESCRIPTION
Reads two PBM, PGM, or PPM files, or PAM equivalents, as
input. Prints the peak signal-to-noise ratio (PSNR) dif
ference between the two images. This metric is typically
used in image compression papers to rate the distortion
between original and decoded image.
If the inputs are PBM or PGM, pnmpsnr prints the PSNR of
the luminance only. Otherwise, it prints the separate
PSNRs of the luminance, and chrominance (Cb and Cr) compo
nents of the colors.
The PSNR of a given component is just the mean square dif
ference of the component, comparing each pixel with the
pixel in the same position of the other image, expressed
as a decibel value. For the purposes of this computation,
components are normalized to the scale [0..1].
SEE ALSO
pnm (5)
Man(1) output converted with
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