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pnmpsnr

Calculate peak signal-to-noise ratio between images

TLDR

Compare two PNM images and display PSNR
$ pnmpsnr [original.pnm] [compressed.pnm]
Compare a JPEG conversion against the original (using Netpbm conversion)
$ pnmpsnr [original.ppm] [converted.ppm]
Compare images from a pipeline (second image from stdin)
$ pnmpsnr [reference.pnm] < [comparison.pnm]

SYNOPSIS

pnmpsnr [file1] [file2]

DESCRIPTION

pnmpsnr calculates the Peak Signal-to-Noise Ratio (PSNR) between two PNM images. PSNR is a standard metric for measuring image quality, commonly used to evaluate the fidelity of compressed or processed images against the original.Higher PSNR values (measured in decibels) indicate greater similarity between the images. Typical values range from 30-50 dB for acceptable quality, while identical images produce an infinite PSNR. For color images, the tool reports PSNR for each channel (red, green, blue) as well as an overall luminance value.Both images must have the same dimensions and depth. Part of the Netpbm toolkit.

PARAMETERS

file1

First input image (reference/original).
file2
Second input image (comparison/distorted). Reads from standard input if omitted.

INSTALL

sudo apt install netpbm
sudo dnf install netpbm
sudo pacman -S netpbm
sudo apk add netpbm
sudo zypper install netpbm
brew install netpbm
nix profile install nixpkgs#netpbm

CAVEATS

Images must have the same dimensions. Only supports PNM/PAM formats; convert other formats first using Netpbm tools. PSNR is not always a reliable indicator of perceptual quality.

SEE ALSO

pnmarith(1), pamarith(1), pamfile(1), pnmcat(1)