vdcomp(1)                                                            vdcomp(1)



Name
       vdcomp - decompress a compressed PDS image

Synopsis
       vdcomp [ infile ] [ outfile ] [ format-code ]

Description
       The  vdcomp  program  reads  a variable length compressed PDS image and
       outputs a fixed length uncompressed  image  file  in  PDS  format  with
       labels,  image  histogram,  engineering table, line header table and an
       image with PDS, FITS, VICAR or no labels.

       If used on a  non-byte-swapped  machine  the  image  histogram  is  un-
       swapped.

Options
       Vdcomp  will  prompt  for any options that are not supplied on the com-
       mand-line.

       infile
              The name of compressed image file.

       outfile
              The name of uncompressed image file.

       format-code
              Select from the following list:
                     1 - SFDU/PDS format [default]
                     2 - FITS format
                     3 - VICAR format
                     4 - unlabelled binary array

Limitations
       This program has been tested on a VAX 780 (VMS  4.6),  SUN  Workstation
       (UNIX  4.2, release 3.4), an IBM PC (MICROSOFT 5.1 compiler) and Macin-
       tosh IIx using Lightspeed C version 3.0.  When converting to other sys-
       tems, check for portability conflicts.

Credits
       This  program uses Kris Becker's subroutine DECOMP.C (which is included
       in this program in a shortened version).

History
       bradley@cis.upenn.edu 06-23-94 ansi-fied program

       datri@convex.com, 11-15-91 added recognition of - as stdout for  output
       filename; disabled various messages; directed messages to stderr; added
       exit status

       DEC89 Modified program to handle both Voyager and Viking images.

       OCT89 Converted Voyager decompression program  to  handle  Viking  com-
       pressed  images.  Changed obuf to 'unsigned' to simplify computation of
       checksum.

       AUG89 Added code to get command line arguments for filenames and output
       format;  routines  to  free memory used by the Huffman tree); fixed the
       SFDU label output length; and modified the I/O  routines  so  that  the
       open for Host type 2 uses binary I/O.

       JUN89 Fixed READVAR, to get length on 16-bit unswapped hosts.

       JUL88 C driver to decompress standard Voyager Compressed images by Mike
       Martin 1989/12/02.



                                                                     vdcomp(1)
