124 lines
3.4 KiB
HTML
124 lines
3.4 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 pnmhistmap</TITLE>
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</HEAD><BODY>
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<H1>pnmhistmap</H1>
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Section: User Commands (1)<BR>Updated: 25 October 1993<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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pnmhistmap - draw a histogram for a PGM or PPM file
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>pnmhistmap</B>
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[<B>-black</B>]
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[<B>-white</B>]
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[<B>-max</B>
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<I>N</I>]
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[<B>-verbose</B>]
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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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although bitmap (PBM) input produces an error message and no image.
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Produces an image showing a histogram of the color (or gray) values
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in the input.
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A graymap (PGM) input produces a bitmap output.
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A pixmap (PPM) input produces pixmap output with three overlaid histograms:
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a red one for the red input,
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a green one for the green input,
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and a blue one for the blue input.
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The output is fixed in size: 256 pixels wide by 200 pixels high.
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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>-black </B>
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<DD>
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Ignores the count of black pixels when scaling the histogram.
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<DT id="2"><B>-white</B>
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<DD>
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Ignores the count of white pixels when scaling the histogram.
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</DL>
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<P>
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The -black and -white options, which can be used seperately or together,
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are useful for images with a large percentage of pixels whose value is
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zero or 255, which can cause the remaining histogram data to become
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unreadbaly small.
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Note that, for pixmap inputs, these options apply to all colors;
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if, for example, the input has a large number of bright-red areas,
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you will probably want to use the -white option.
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<DL COMPACT>
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<DT id="3"><B>-max N</B>
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<DD>
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Force the scaling of the histogram to use N as the largest-count value.
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This is useful for inputs with a large percentage of single-color pixels
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which are not black or white.
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<DT id="4"><B>-verbose</B>
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<DD>
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Report the progress of making the histogram, including the largest-count
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value used to scale the output.
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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>BUGS</H2>
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<P>
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Assumes maxval is always 255.
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Images with a smaller maxval will only use the lower-value side of the
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histogram.
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This can be overcome either by piping the input through "pnmdepth 255"
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or by cutting and scaling the lower-value side of the histogram.
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Neither is a particularly elegant solution.
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<P>
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Should allow the output size to be specified.
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<A HREF="/cgi-bin/man/man2html?1+pgmhist">pgmhist</A>(1), <A HREF="/cgi-bin/man/man2html?1+ppmhist">ppmhist</A>(1), <A HREF="/cgi-bin/man/man2html?5+pgm">pgm</A>(5), <A HREF="/cgi-bin/man/man2html?5+ppm">ppm</A>(5)
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<A NAME="lbAH"> </A>
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<H2>AUTHOR</H2>
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Wilson H. Bent. Jr. (<A HREF="mailto:whb@usc.edu">whb@usc.edu</A>).
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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="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="9"><A HREF="#lbAF">BUGS</A><DD>
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<DT id="10"><A HREF="#lbAG">SEE ALSO</A><DD>
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<DT id="11"><A HREF="#lbAH">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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