NAME

     wvh2 - Wavelet -  Variance  Quantization  -  Huffman  Coding
     Compression

SYNOPSIS

     wvh2 [ -Nntap ] [ -Ootap ] [ -crcr ] [ -lxlx ] [ -lsls  ]  [
     -V ] [ -h ] [ -? ]

DESCRIPTION

     wvh2 performs wavelet variance quantization huffman  coding.
     The  algorithm  uses 2-D wavelet tensor transform algorithm,
     variance quantization and Huffman coding.
     wvh2 gets both its data and its parameters from command line
     arguments.   These  arguments specify the input, output, the
     compression ratio, the trace wavelet transform decomposition
     levels,  the time wavelet transform decomposition levels and
     verbose printout, if desired.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing -N unless the input is from a pipe in which case
          the -N entry must be omitted.  This input  file  should
          include the complete path name if the file resides in a
          different directory.  Example -N/b/vsp/dummy tells  the
          program to look for file 'dummy' in directory '/b/vsp'.

     -O otap
          Enter the output data  set  name  or  file  immediately
          after typing -O.  This output file is not required when
          piping the output to another process.  The output  data
          set also requires the full path name (see above).

     -cr cr
          Enter the compression ratio.  The default is the  value
          of  15.  For the default value, in prestack data we get
          visually lossless compression.

     -lx lx
          Enter the trace wavelet transform decomposition levels.
          The  default  value  is  5.  We  need  to be careful in
          selecting this number of levels. For number  of  traces
          higher or equal than 32, set lx=5. For number of traces
          between 16 and 32,  set  lx=4.  For  number  of  traces
          between 8 and 15, set lx=3

     -ls ls
          Enter the time wavelet transform decomposition  levels.
          The default value is 5.

     -V   Enter the command line argument '-V' to get  additional
          printout.

     -? or -h
          Enter the command line argument '-?'  or   -h   to  get
          online  help.   The  program  terminates after the help
          screen is printed.

DISCUSSION

     This code performs 2-D Wavelet tensor -  Variance  quantiza-
     tion  - Huffman coding compression of seismic data. The out-
     put compressed file starts with  the  seismic  header  loss-
     lessly  compressed  by  gzip,  the compression header (which
     includes parameters, such as wavelet filter lenghts, quanti-
     zation  bin  widths,  Huffman codes) followed by the Huffman
     coded, quantized, 2-D wavelet tensor transform coefficients.

     It is important to have amplitude balanced data  going  into
     this  routine.   By  balanced we mean at least corrected for
     spherical divergence.  A simple  ttothen  does the trick  on
     most  data.   The more attention paid to preconditioning the
     data  for  compression  [direct  arrival  removal,  bandpass
     filtering,   spherical  divergence  compensation  etc.]  the
     greater the compression attained and the lower the residuals
     after a cycle of compression / decompression.

     This  product  is  licensed  from  GeoEnergy  Inc.   It   is
     proprietary  to  BP  Amoco and may not be ported to applica-
     tions or locations outside the company without the expressed
     written permission

BUGS

     None known up to this point

AUTHOR

     Anthony Vassiliou (GeoEnergy Inc.  918-494-4641),  Joe  Wade
     (socon 421-3324)

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.