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COMPFACE(3)		   Library Functions Manual		   COMPFACE(3)

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

       compface	(buf)

       uncompface (buf)

       char *buf

       compface	is a function for generating highly compressed representations
       of 48x48x1 face image files.  uncompface	is an inverse  function	 which
       performs	an inverse transformation 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 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 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 fol-
       lowed 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.

       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 over-
       run occurs.


				15 January 2002			   COMPFACE(3)


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