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 transfor-
       mation 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 functions,
       input is via a NULL terminated string and  a  NULL  termi-
       nated 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 generation.

       The  input  format for compface (and the output format for
       uncompface) is 48 lines each of 3 sixteen bit  hexadecimal
       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 operation.
       -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			1

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