doc/C/hilo.html

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   6 \fP
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   8 .SH DESCRIPTION
   9
  10 \fIhilo\fP is a low-band pass
  11 filter for removing (non-homogeneos) background illumination and
  12 maximizing the contrast of images. For this purpose it searches for
  13 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
  14 found. The envelopes are smoothed by linear interpolation. For each
  15 pixel in the image the minimum envelope is substracted from the pixel
  16 value and the maximum envelope is stretched to the maximum pixel
  17 value, defined by the number of bits a pixel is represented (255
  18 for 8 bits image)
  19
  20 The parameters and options to be used for \fIhilo\fP are subsequently
  21 searched in \fI\fIhilo.par\fR at local directory, at
  22 \fI~/.gpivrc\fR or at \fI/etc/gpivrc\fR. Except for the number of input data, each parameter is
  23 described by the program key (F_HL) and the parameter name, separated
  24 by a dot (.), followed by its value. The parameters may be defined in
  25 arbitrary order. Blank lines and comment (starting with a pound sign
  26 (#) at the first column) may be included in the parameter files.  The
  27 parameters may be overruled by the command line options, as explained
  28 below.
  29
  30 .SH Options
  31 .TP
  32 \fB-b \fIN\fP
  33 The number of bits \fIN\fR that represent the pixel value (depth).
  34 .TP
  35 \fB-c \fIN\fP
  36 Number of columns \fIN\fR that contains the image.
  37 .TP
  38 \fB-f \fIfilename\fP Opens file \fIfilename.r\fR for reading the image
  39 and writes the output to \fIfilename.fhl\fR. The number of rows and
  40 columns are read from \fIfilename.h\fR, if exists. The \fIfilename\fR
  41 has to be given without its \fB.r\fR extension. The output will be
  42 written to \fIfilename\fB.fhl.r\fR.
  43 .TP
  44 \fB-h\fP
  45 On-line help
  46 .TP
  47 \fB-p\fP
  48 Print parameters, command line options and eventually used input and
  49 output filenames to stdout. The output may be used as parameters of
  50 \fBhilo\fP for future use by re-directing stdout to \fBhilo.par\fR.
  51 .TP
  52 \fB-v\fP
  53 Print version information on standard output, then exit successfully.
  54 .TP
  55 \fB-r \fIN\fP
  56 Number of rows \fIN\fR that contains the image.
  57 Gerber Van der Graaf
  58
  59 .SH BUGS
  60 So far: none.
  61
  62
  63
  64
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