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diff --git a/pnmpsnr.html b/pnmpsnr.html new file mode 100644 index 00000000..296a8dca --- /dev/null +++ b/pnmpsnr.html @@ -0,0 +1,71 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML><HEAD><TITLE>Pnmpsnr User Manual</TITLE></HEAD> +<BODY> +<H1>pnmpsnr</H1> +Updated: 04 March 2001 +<BR> +<A HREF="#index">Table Of Contents</A> + +<A NAME="lbAB"> </A> +<H2>NAME</H2> + +pnmpsnr - compute the difference between two images (the PSNR) + +<A NAME="lbAC"> </A> +<H2>SYNOPSIS</H2> + +<B>pnmpsnr</B> + +[<I>pnmfile1</I>] + +[<I>pnmfile2</I>] + +<A NAME="lbAD"> </A> +<H2>DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<p><b>pnmpsnr</b> reads two PBM, PGM, or PPM files, or PAM +equivalents, as input and prints the peak signal-to-noise ratio (PSNR) +difference between the two images. This metric is typically used in +image compression papers to rate the distortion between original and +decoded image. + +<P>If the inputs are PBM or PGM, <B>pnmpsnr</B> prints the PSNR of the +luminance only. Otherwise, it prints the separate PSNRs of the +luminance, and chrominance (Cb and Cr) components of the colors. + +<P>The PSNR of a given component is the ratio of the mean square +difference of the component for the two images to the maximum mean +square difference that can exist between any two images. It is +expressed as a decibel value. + +<P>The mean square difference of a component for two images is the +mean square difference of the component value, comparing each pixel +with the pixel in the same position of the other image. For the +purposes of this computation, components are normalized to the scale +[0..1]. + +<P>The maximum mean square difference is identically 1. + +<P>So the higher the PSNR, the closer the images are. A luminance +PSNR of 20 means the mean square difference of the luminances of the +pixels is 100 times less than the maximum possible difference, +i.e. 0.01. + +<A NAME="lbAE"> </A> +<H2>SEE ALSO</H2> + +<B><A HREF="pnm.html">pnm</A></B> + +<HR> +<A NAME="index"> </A> +<H2>Table Of Contents</H2> +<UL> +<LI><A HREF="#lbAB">NAME</A> +<LI><A HREF="#lbAC">SYNOPSIS</A> +<LI><A HREF="#lbAD">DESCRIPTION</A> +<LI><A HREF="#lbAE">SEE ALSO</A> +</UL> +</BODY> +</HTML> |