COMPFACE(3)                                         COMPFACE(3)





NAME
       compface,  uncompface - compress and expand 48x48x1 face
       image files

SYNOPSIS
       compface (buf)

       uncompface (buf)

       char *buf

DESCRIPTION
       compface is a function for generating highly  compressed
       representations of 48x48x1 face image files.  uncompface
       is an inverse function which performs an inverse  trans-
       formation  with  no loss of data.  The algorithm used is
       highly tuned for its purpose and achieves better than  a
       five to one compression ratio on average.  In both func-
       tions, input is via a NULL terminated string and a  NULL
       terminated  output  string  is  written  over  the input
       string.  Buf should therefore point to  a  block  of  2K
       size or more to avoid buffer overruns during output gen-
       eration.

       The input format for compface (and the output format for
       uncompface)  is 48 lines each of 3 sixteen bit hexadeci-
       mal integers, comma terminated in C  initialiser  style.
       The  output format of compface (and the input format for
       uncompface) is some number of lines made up of  a  space
       followed  by printable characters (in the range ``!'' to
       ``~'' inclusive).  The first line contains 72 characters
       and  following  lines  contain 79 characters except that
       the last line may be short.

       The amount of compression obtained varies  between  face
       image  files  but  the  output of compface averages less
       than 200 characters.  The average number of output lines
       is three.

DIAGNOSTICS
       The  return  value is normally 0.  1 will be returned if
       extra input has been ignored during  a  compress  opera-
       tion.   -1  is  returned in the case of an invalid input
       format.  -2 is returned if an  internal  buffer  overrun
       occurs.

SEE ALSO
       Compface(1)



                        25 January 1990             COMPFACE(3)
