179 lines
4.7 KiB
HTML
179 lines
4.7 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 pngtopnm</TITLE>
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</HEAD><BODY>
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<H1>pngtopnm</H1>
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Section: User Commands (1)<BR>Updated: 6 January 1997<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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pngtopnm - convert a Portable Network Graphics file into portable anymap
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>pngtopnm</B>
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[-verbose]
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[-alpha | -mix]
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[-background color]
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<BR>
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[-gamma value]
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[-text file]
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[-time]
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[<I>pngfile</I>]
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Reads a Portable Network Graphics as input.
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<A NAME="ixAAC"></A>
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Produces a portable anymap as output.
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The type of the output file depends on the input file - if it's
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black & white, a
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<I>pbm</I>
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file is written, else if it's grayscale a
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<I>pgm</I>
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file, else a
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<I>ppm</I>
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file.
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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<DL COMPACT>
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<DT id="1"><B>-verbose</B>
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<DD>
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Display the format of the input file and the type of the output file. If
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the chunks are part of the
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<I>png-file,</I>
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the alpha, transparency and gamma-values will be indicated.
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<DT id="2"><B>-alpha</B>
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<DD>
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Output the alpha channel or transparency mask of the image. The result is either a
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<I>pbm</I>
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file or
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<I>pgm</I>
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file, depending on whether different levels of transparency appear.
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<DT id="3"><B>-mix</B>
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<DD>
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Compose the image with the transparency or alpha mask against a the
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background. When a background chunk is available that color is taken,
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else black will do.
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<DT id="4"><B>-background color</B>
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<DD>
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If no background color chunck is present in the
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<I>png-file,</I>
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or when another color is required this parameter can be used to set the
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background color of images. This is especially useful for alpha-channel
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images or those with transparency chunks. The format, to specify the color in,
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is either (in the case of orange) "1.0,0.5,0.0", where the values are floats
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between zero and one, or with the syntax "#RGB", "#RRGGBB" or "#RRRRGGGGBBBB"
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where R, G and B are hexa-decimal numbers.
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<DT id="5"><B>-gamma value</B>
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<DD>
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Converts the image to a new display-gamma value. When a gAMA chunk is present
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in the
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<I>png-file,</I>
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the image-gamma value will be used. When not, the image-gamma is considered
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to be 1.0. Based on the image-gamma and the display-gamma given with this
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option the colors written to the
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<I>pnm-file</I>
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will be adjusted.
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<BR>
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Because the gamma's of uncompensated monitors are around 2.6, which results
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in an image-gamma of 0.45, some typical situations are:
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when the image-gamma is 0.45 (use -verbose to check) and the picture is too
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light, your system is gamma-corrected, so convert with "-gamma 1.0".
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When no gAMA chunk is present or the image-gamma is 1.0, use 2.2 to make the
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picture lighter and 0.45 to make the picture darker.
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<DT id="6"><B>-text file</B>
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<DD>
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Writes the tEXt and zTXt chunks to a file, in a format as described in the
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<I>pnmtopng</I>
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man-page. These chunks contain text comments or annotations.
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<DT id="7"><B>-time</B>
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<DD>
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Prints the tIME chunk to stderr.
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</DL>
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<P>
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All flags can be abbreviated to their shortest unique prefix.
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<A NAME="lbAF"> </A>
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<H2>SEE ALSO</H2>
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<A HREF="/cgi-bin/man/man2html?1+pnmtopng">pnmtopng</A>(1), <A HREF="/cgi-bin/man/man2html?1+ptot">ptot</A>(1), <A HREF="/cgi-bin/man/man2html?1+pnmgamma">pnmgamma</A>(1), <A HREF="/cgi-bin/man/man2html?5+pnm">pnm</A>(5)
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<A NAME="lbAG"> </A>
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<H2>NOTE</H2>
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Instead of pngtopnm|pnmtoxxx, a specific converter should be used, if
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available. E.g.
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<I>ptot</I>
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(PNG to TIFF conversion), etc.
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<A NAME="lbAH"> </A>
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<H2>BUGS</H2>
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There could be an option to read the comment text from pnm comments instead
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of a separate file.
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<P>
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The program could be much faster, with a bit of code optimizing.
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<A NAME="lbAI"> </A>
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<H2>AUTHORS</H2>
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Copyright (C) 1995-1997 by Alexander Lehmann
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<BR>
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<BR> and Willem van Schaik.
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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="8"><A HREF="#lbAB">NAME</A><DD>
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<DT id="9"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="10"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="11"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="12"><A HREF="#lbAF">SEE ALSO</A><DD>
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<DT id="13"><A HREF="#lbAG">NOTE</A><DD>
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<DT id="14"><A HREF="#lbAH">BUGS</A><DD>
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<DT id="15"><A HREF="#lbAI">AUTHORS</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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</BODY>
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</HTML>
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