doc/C/hilo.html

   1 <HTML><HEAD><TITLE>Manpage of </TITLE>
   2 </HEAD><BODY BGCOLOR="#FFFFFF">
   3 Name: <B>HILO</B><BR>
   4 Section: User Commands  (1)
   5 <HR>
   6
   7 <A NAME="lbAB">&nbsp;</A>
   8 <H2>NAME</H2>
   9
  10 hilo - Low-pass filter for removing non-uniform background and
  11 maximizing contrast in (PIV) imgages
  12 <A NAME="lbAC">&nbsp;</A>
  13 <H2>SYNOPSIS</H2>
  14
  15 <P>
  16 <B>hilo</B> [<B>-b int</B>][<B>-c int</B>][<B>-h</B>][<B>-f filename</B>][<B>-p</B>][<B>-r int</B>][<B>-v</B>][<B>-w</B>] &lt; <I>stdin</I> &gt; <I>stdoutfR
  17 <P>
  18 </I>
  19 <P>
  20 <A NAME="lbAD">&nbsp;</A>
  21 <H2>DESCRIPTION</H2>
  22
  23 <P>
  24 <I>hilo</I> is a low-band pass
  25 filter for removing (non-homogeneos) background illumination and
  26 maximizing the contrast of images. For this purpose it searches for
  27 each pixel the highest and lowest pixel value within a window. By moving the window over the image, a maximum and a minimum envelope is
  28 found. The envelopes are smoothed by linear interpolation. For each
  29 pixel in the image the minimum envelope is substracted from the pixel
  30 value and the maximum envelope is stretched to the maximum pixel
  31 value, defined by the number of bits a pixel is represented (255
  32 for 8 bits image)
  33 <P>
  34 The parameters and options to be used for <I>hilo</I> are subsequently
  35 searched in <I>hilo.par</I> at local directory, at
  36 <I>~/.gpivrc</I> or at <I>/etc/gpivrc</I>. Except for the number of input data, each parameter is
  37 described by the program key (F_HL) and the parameter name, separated
  38 by a dot (.), followed by its value. The parameters may be defined in
  39 arbitrary order. Blank lines and comment (starting with a pound sign
  40 (#) at the first column) may be included in the parameter files.  The
  41 parameters may be overruled by the command line options, as explained
  42 below.
  43 <P>
  44 <A NAME="lbAE">&nbsp;</A>
  45 <H2>Options </H2>
  46
  47 <DL COMPACT>
  48 <DT><B>-b </B><I>N</I><DD>
  49 The number of bits <I>N</I> that represent the pixel value (depth).
  50 <DT><B>-c </B><I>N</I><DD>
  51 Number of columns <I>N</I> that contains the image.
  52 <DT><B>-f </B><I>filename</I> Opens file <I>filename.r</I> for reading the image<DD>
  53 and writes the output to <I>filename.fhl</I>. The number of rows and
  54 columns are read from <I>filename.h</I>, if exists. The <I>filename</I>
  55 has to be given without its <B>.r</B> extension. The output will be
  56 written to <I>filename</I><B>.fhl.r</B>.
  57 <DT><B>-h</B><DD>
  58 On-line help
  59 <DT><B>-p</B><DD>
  60 Print parameters, command line options and eventually used input and
  61 output filenames to stdout. The output may be used as parameters of
  62 <B>hilo</B> for future use by re-directing stdout to <B>hilo.par</B>.
  63 <DT><B>-v</B><DD>
  64 Print version information on standard output, then exit successfully.
  65 <DT><B>-r </B><I>N</I><DD>
  66 Number of rows <I>N</I> that contains the image.
  67 <DT><B>-w </B><I>N</I><DD>
  68 Window size <I>N</I> will be used for calculating the local maximum and
  69 minimum pixel value.
  70 <DT><DD>
  71 </DL>
  72 <A NAME="lbAF">&nbsp;</A>
  73 <H2>SEE ALSO</H2>
  74
  75 batch-gp, dav2piv, err_vec, manipiv, hilo, rr, scale, s-avg, t-avg, peaklck,
  76 piv2vec,vorstra
  77 <P>
  78 <A NAME="lbAG">&nbsp;</A>
  79 <H2>NOTES</H2>
  80
  81 The program has been tested and validated with artificial images.
  82 <P>
  83 <A NAME="lbAH">&nbsp;</A>
  84 <H2>AUTHOR</H2>
  85
  86 Gerber Van der Graaf
  87 <P>
  88 <A NAME="lbAI">&nbsp;</A>
  89 <H2>BUGS</H2>
  90
  91 So far: none.
  92 <P>
  93 <P>
  94 <P>
  95 <P>
  96 <P>
  97
  98 <HR>
  99 <A NAME="index">&nbsp;</A><H2>Table of Contents</H2>
 100 <OL>
 101 <LI><A HREF="#lbAB">Name</A>
 102 <LI><A HREF="#lbAC">Synopsis</A>
 103 <LI><A HREF="#lbAD">Description</A>
 104 <LI><A HREF="#lbAE">Options </A>
 105 <LI><A HREF="#lbAF">See also</A>
 106 <LI><A HREF="#lbAG">Notes</A>
 107 <LI><A HREF="#lbAH">Author</A>
 108 <LI><A HREF="#lbAI">Bugs</A>
 109 </OL>
 110 </BODY>
 111 </HTML>