175 lines
4.6 KiB
HTML
175 lines
4.6 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 pgmtoppm</TITLE>
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</HEAD><BODY>
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<H1>pgmtoppm</H1>
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Section: User Commands (1)<BR>Updated: 24 January 2001<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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pgmtoppm - colorize a portable graymap into a portable pixmap
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>pgmtoppm</B>
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<I>colorspec</I>
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[<I>pgmfile</I>]
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<BR>
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<B>pgmtoppm</B>
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<I>colorspec1</I><B>-</B><I>colorspec2</I>
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[<I>pgmfile</I>]
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<BR>
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<B>pgmtoppm -map</B>
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<I>mapfile</I>
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[<I>pgmfile</I>]
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<P>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Reads a PGM as input. Produces a PPM file as output with a specific color
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assigned to each gray value in the input.
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<A NAME="ixAAC"></A>
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<P>
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If you specify one color argument, black in the pgm file stays black
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and white in the pgm file turns into the specified color in the ppm
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file. Gray values in between are linearly mapped to differing
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intensities of the specified color.
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<P>
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If you specify two color arguments (separated by a dash), then black
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gets mapped to the first color and white gets mapped to the second and
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gray values in between get mapped linearly (across a three dimensional
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space) to colors in between.
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<P>
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You can specify the color in one of five ways:
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<DL COMPACT>
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<DT id="1">o<DD>
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A name, from an X11-style color names file.
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<DT id="2">o<DD>
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An X11-style hexadecimal specifier: rgb:r/g/b, where r g and b are
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each 1- to 4-digit hexadecimal numbers.
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<DT id="3">o<DD>
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An X11-style decimal specifier: rgbi:r/g/b, where r g and b are
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floating point numbers between 0 and 1.
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<DT id="4">o<DD>
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For backwards compatibility, an old-X11-style hexadecimal
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number: #rgb, #rrggbb, #rrrgggbbb, or #rrrrggggbbbb.
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<DT id="5">o<DD>
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For backwards compatibility, a triplet of numbers
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separated by commas: r,g,b, where r g and b are
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floating point numbers between 0 and 1.
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(This style was added before MIT came up with the similar rgbi style.)
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</DL>
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<P>
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Also, you can specify an entire colormap with the
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<B>-map</B>
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option.
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The mapfile is just a
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<B>ppm</B>
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file; it can be any shape, all that matters is the colors in it and
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their order. In this case, black gets mapped into the first color in
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the map file, and white gets mapped to the last and gray values in
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between are mapped linearly onto the sequence of colors in between.
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<P>
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<A NAME="lbAE"> </A>
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<H2>NOTE - MAXVAL</H2>
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<P>
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The "maxval," or depth, of the output image is the same as that of the
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input image. The maxval affects the color resolution, which may cause
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quantization errors you don't anticipate in your output. For example,
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you have a simple black and white image (in fact, let's say it's a
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PBM file, since
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<B>pgmtoppm</B>,
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like all Netpbm programs, can accept a PBM file as if it were PGM.
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The maxval of this image is 1, because only two gray values are needed:
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black and white. Run this image through
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<B>pgmtoppm 0f/00/00</B>
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to try to make the image black and faint red. Because the output image
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will also have maxval 1, there is no such thing as faint red. It has
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to be either full-on red or black.
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<B>pgmtoppm</B>
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rounds the color 0f/00/00 down to black, and you get an output image
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that is nothing but black.
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<P>
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The fix is easy: Pass the input through
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<B>pnmdepth</B>
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on the way into
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<B>pgmtoppm</B>
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to increase its depth to something that would give you the resolution you
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need to get your desired color. In this case,
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<B>pnmdepth 16</B>
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would do it. Or spare yourself the unnecessary thinking and just say
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<B>pnmdepth 255 .</B>
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<P>
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<A NAME="lbAF"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?1+pnmdepth">pnmdepth</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?1+rgb3toppm">rgb3toppm</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?1+ppmtopgm">ppmtopgm</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?1+ppmtorgb3">ppmtorgb3</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?5+ppm">ppm</A></B>(5),
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<B><A HREF="/cgi-bin/man/man2html?5+pgm">pgm</A>(5)</B>
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<P>
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<A NAME="lbAG"> </A>
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<H2>AUTHOR</H2>
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Copyright (C) 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="6"><A HREF="#lbAB">NAME</A><DD>
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<DT id="7"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="8"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="9"><A HREF="#lbAE">NOTE - MAXVAL</A><DD>
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<DT id="10"><A HREF="#lbAF">SEE ALSO</A><DD>
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<DT id="11"><A HREF="#lbAG">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: 00:05:23 GMT, March 31, 2021
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