COMPFACE(3) COMPFACE(3)
25 January 1990
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 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 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)
- 1 - Formatted: April 19, 2024
