gen_koch_sig(1)

NAME
gen_koch_sig - a program to generate a signature for the wm_koch_e watermarking program

SYNOPSIS
gen_koch_sig [ -h ] [ -n number ] [ -o file ] [ -q number ] [ -s number ] [ file ]

DESCRIPTION
gen_koch_sig is a program to generate a signature to be embedded with the wm_koch_e watermarking program and extracted with the wm_koch_d program. The cmp_koch_sig program is used to compare and test an extracted signature with the original signature.

Please refer to E. Koch's paper "Towards Robust and Hidden Image Copyright", 1995, to get an idea about the algorithm.

OPTIONS

-h  Print a help message.

-n number
    Limit the signature length to number bits (0 < number <= 1024) unless reading from standard input. When reading from standard input, the signature is terminated by the first carriage return character.

-o file
    Output signature to the specified file instead of standard output.

-q number
    Quality/robustness factor used to embed signature into image. Default value: 3.0.

-s number
    Specify a seed value to initialize the pseudo-random number generator; if not specified, time and pid (process id) are used to initialize the pseudo-random number generator.

file
    Input file to read raw signature data from. Default: standard input.

OUTPUT
The output file has the following format:

KCSG
    Magic to identify file type.

number
    The length of the signature in bits.

number
    The quality/robustness factor.

number
    The seed value for the pseudo-random number generator.

string
    The actual signature bytes.

AUTHOR
Peter Meerwald. Email bug reports to pmeerw@cosy.sbg.ac.at.

AVAILABILITY
The most recent released version of gen_koch_sig is always available at http://www.cosy.sbg.ac.at/~pmeerw/Watermarking or via anonymous ftp from ftp.cosy.sbg.ac.at in the directory /pub/people/pmeerw/Watermarking.

SEE ALSO
wm_koch_e (1), wm_koch_d (1), cmp_koch_sig (1)