Usage: WlzHistogramData [-h] [-o< out file >] [< in object >]
      Options:
      -o Output data file name.
      -h Help, prints this usage message.
      Reads a Woolz histogram object and writes it as ascii data.
      Objects/data are read from stdin and written to stdout unless the
      filenames are given.
      Example: WlzHistogramData myHist.wlz | xgraph
      The input Woolz histogram object is read from myHist.wlz, and
      written as ascii data for display by the program xgraph.