NAME

       gpiv_peaklck  - Tests PIV data on the so-called peak-locking effect by printing/displaying
       an histogram of the particle displacements at sub-pixel level.

SYNOPSIS

       gpiv_peaklck [-g] [-h | --help] [-n N] [-p | --print] [-v | --version] [filename] <  stdin
       > stdout

DESCRIPTION

       Peak-locking  effects  in  Particle Image Velocimetry (PIV) result into estimations of the
       particle displacements that are mainly at an integer number of pixels, instead of at  sub-
       pixel displacements. This effect may due to stretching of the (round) pixel images, due to
       a too low resolution of the pixel-image or may be due to signal interferences of the  data
       from   camera  to  frame  grabber.   Gpiv_Peaklck  calculates  the  particle  displacement
       distribution at sub-pixel level in between 0.0 an 1.0 (0 included, 1  excluded).  If  peak
       locking occurs, a non-uniform distribution of the estimated particle displacements at sub-
       pixel level will be found.

       The configuration parameters (containing the VALID key) may be overruled  by  the  command
       line options, as explained below.

Options

       -g     Graphical visualization of the histogram with gnuplot.

       -h | --help
              On-line help

       -n N   Override number of bins (default 10, hard coded).

       -p | --print
              Print  parameters,  command  line  options  and  eventually  used  input and output
              filenames to stdout.  The output is identic of filename.par, in case -f is used.

       -v | --version
              Print version information on standard output, then exit successfully.

       filename
              Input PIV data file.  Overrides  stdin  and  stdout.  Output  will  be  written  to
              filename.plk. The parameters will be written or appended to filename.par and may be
              used for future use by including them in ./gpivrc.

SEE ALSO

       gpivtools

AUTHOR

       Gerber Van der Graaf

BUGS

       The program seems to work fine with real PIV data.  So far,  no  serious  bugs  have  been
       found.

                                         8 November 2006                          GPIV_PEAKLCK(1)