pnmpsnr

 

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 pnmpsnr(1)                                             pnmpsnr(1)
 
 
 
NAME
        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)
 
 
 
                           04 March 2001                pnmpsnr(1)

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