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| author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
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| committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
| commit | 1017cbebe5d5edd859e0fddad0a8600f509f4821 (patch) | |
| tree | 78bdf336648566f7a7d55f42837357dea3dd674c /pgmtoppm.html | |
| parent | 16f2ac126651015a376eba864a3a35f738b0b25a (diff) | |
| download | netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.gz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.xz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.zip | |
Place user guide into Subversion repository
git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@181 9d0c8265-081b-0410-96cb-a4ca84ce46f8
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| -rw-r--r-- | pgmtoppm.html | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/pgmtoppm.html b/pgmtoppm.html new file mode 100644 index 00000000..ea93a60c --- /dev/null +++ b/pgmtoppm.html @@ -0,0 +1,121 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML><HEAD><TITLE>Pgmtoppm User Manual</TITLE></HEAD> +<BODY> +<H1>pgmtoppm</H1> +Updated: 10 December 2006 +<BR> +<A HREF="#index">Table Of Contents</A> + +<H2>NAME</H2> + +pgmtoppm - colorize a PGM (grayscale) image into a PPM (color) image + +<H2 id="synopsis">SYNOPSIS</H2> + +<B>pgmtoppm</B> + +<I>colorspec</I> + +[<I>pgmfile</I>] + +<BR> + +<B>pgmtoppm</B> + +<I>colorspec1</I><B>-</B><I>colorspec2</I> + +[<I>pgmfile</I>] + +<BR> + +<B>pgmtoppm</b> +<b>-map=</B><I>mapfile</I> + +[<I>pgmfile</I>] + +<P>Minimum unique abbreviation of option is acceptable. You may use double +hyphens instead of single hyphen to denote options. You may use white +space in place of the equals sign to separate an option name from its value. + +<H2 id="description">DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<p><b>pgmtoppm</b> reads a PGM as input and produces a PPM file as +output with a specific color assigned to each gray value in the input. + +<P>If you specify one color argument, black in the pgm file stays +black and white in the pgm file turns into the specified color in the +ppm file. Gray values in between are linearly mapped to differing +intensities of the specified color. + +<P>If you specify two color arguments (separated by a hyphen), then +black gets mapped to the first color and white gets mapped to the +second and gray values in between get mapped linearly (across a three +dimensional space) to colors in between. + +<P>Specify the color (<i>color</i>) as described for the <a +href="libppm.html#colorname">argument of the <b>ppm_parsecolor()</b> +library routine</a>. + +<p>Also, you can specify an entire colormap with the <B>-map</B> +option. The mapfile is just a <B>ppm</B> file; it can be any shape, +all that matters is the colors in it and their order. In this case, +black gets mapped into the first color in the map file, and white gets +mapped to the last and gray values in between are mapped linearly onto +the sequence of colors in between. The maxval of the output image is +the maxval of the map image. + +<p>A more direct way to specify a particular color to replace each +particular gray level is to use <b>pamlookup</b>. You make an index +file that explicitly associates a color with each possible gray level. + +<H2 id="maxval">NOTE - MAXVAL</H2> + +<P>When you don't use <b>-map</b>, the "maxval," or depth, +of the output image is the same as that of the input image. The +maxval affects the color resolution, which may cause quantization +errors you don't anticipate in your output. For example, you have a +simple black and white image as a PGM with maxval 1. Run this image +through <B>pgmtoppm 0f/00/00</B> to try to make the image black and +faint red. Because the output image will also have maxval 1, there is +no such thing as faint red. It has to be either full-on red or black. +<B>pgmtoppm</B> rounds the color 0f/00/00 down to black, and you get +an output image that is nothing but black. + +<P>The fix is easy: Pass the input through <B>pamdepth</B> on the way +into <B>pgmtoppm</B> to increase its depth to something that would +give you the resolution you need to get your desired color. In this +case, <B>pamdepth 16</B> would do it. Or spare yourself the +unnecessary thinking and just say <B>pamdepth 255</B>. + +<p>PBM input is a special case. While you might think this would be +equivalent to a PGM with maxval 1 since only two gray levels are +necessary to represent a PBM image, <b>pgmtoppm</b>, like all Netpbm +programs, in fact treats it as a maxval of 255. + +<H2 id="seealso">SEE ALSO</H2> + +<B><A HREF="pamdepth.html">pamdepth</A></B>, +<B><A HREF="rgb3toppm.html">rgb3toppm</A></B>, +<B><A HREF="ppmtopgm.html">ppmtopgm</A></B>, +<B><A HREF="ppmtorgb3.html">ppmtorgb3</A></B>, +<B><A HREF="ppm.html">ppm</A></B>, +<B><A HREF="pgm.html">pgm</A></B> + +<H2 id="author">AUTHOR</H2> + +Copyright (C) 1991 by Jef Poskanzer. + +<HR> +<A NAME="index"> </A> +<H2>Table Of Contents</H2> +<UL> +<LI><A HREF="#synopsis">SYNOPSIS</A> +<LI><A HREF="#description">DESCRIPTION</A> +<LI><A HREF="#maxval">NOTE - MAXVAL</A> +<LI><A HREF="#seealso">SEE ALSO</A> +<LI><A HREF="#author">AUTHOR</A> +</UL> +</BODY> +</HTML> |