81 lines
2.0 KiB
HTML
81 lines
2.0 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of pnmdepth</TITLE>
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</HEAD><BODY>
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<H1>pnmdepth</H1>
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Section: User Commands (1)<BR>Updated: 08 April 2000<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="ixAAB"></A>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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pnmdepth - change the maxval in a portable anymap
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>pnmdepth</B>
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<I>newmaxval</I>
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[<I>pnmfile</I>]
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Reads a portable anymap as input.
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Scales all the pixel values, and writes out the image with the new maxval.
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Scaling the colors down to a smaller maxval will result in some loss
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of information.
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<P>
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Be careful of off-by-one errors when choosing the new maxval.
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For instance, if you want the color values to be five bits wide,
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use a maxval of 31, not 32.
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<P>
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One important use of
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<B>pnmdepth</B>
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is to convert a new format 2-byte-per-sample PNM file to the older
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1-byte-per-sample format. Before April 2000, essentially all raw
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(binary) format PNM files had a maxval less than 256 and one byte per
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sample, and many programs may rely on that. If you specify a
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<I>newmaxval</I>
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less than 256, the resulting file should be readable by any program
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that worked with PNM files before April 2000.
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<P>
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<A NAME="lbAE"> </A>
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<H2>SEE ALSO</H2>
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<A HREF="/cgi-bin/man/man2html?5+pnm">pnm</A>(5), <A HREF="/cgi-bin/man/man2html?1+ppmquant">ppmquant</A>(1), <A HREF="/cgi-bin/man/man2html?1+ppmdither">ppmdither</A>(1)
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<A NAME="lbAF"> </A>
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<H2>AUTHOR</H2>
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Copyright (C) 1989, 1991 by Jef Poskanzer.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">SEE ALSO</A><DD>
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<DT id="5"><A HREF="#lbAF">AUTHOR</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:24 GMT, March 31, 2021
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</BODY>
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</HTML>
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