.\"
.\" wm_koch_e.1 - the *roff document processor man page source
.\"
.TH wm_koch_e 1 "98/07/05" "Watermarking, Version 1.0"
.SH NAME
.B wm_koch_e
\- a program to embed signature bits in the DCT coefficients of an image
.SH SYNOPSIS
.B wm_koch_e
[
.B \-h
]
[
.BI \-o \ ofile
]
[
.BI \-q \ number
]
[
.BI \-v \ number
]
.BI \-s \ sfile
.IR file
.SH DESCRIPTION
.B wm_koch_e
is a program to embed signature bits in 8x8 DCT coefficients of
an image. The signature has to be generated by the
.B gen_koch_sig
program. The
.B wm_koch_d
program is used to extract a signature from a signed (watermarked) image. The
.B cmp_koch_sig
program compares and tests the extracted signature against the original signature.
.PP
Both, input and output image,
are in PGM (portable graymap) format.
.PP
If
.I file
or
.I ofile
is not specified, then standard input or standard output is
used. The signature
.I sfile
is a mandatory parameter however.
.PP
Please refer to E. Koch's paper "Towards Robust and Hidden
Image Copyright", 1995, to get an idea about the algorithm.
.PP
.SH OPTIONS
.TP
.B \-h
Print a help message.
.TP
.BI \-o \ ofile
Output signed (watermarked) image to
.I ofile
instead of standard output.
.TP
.BI \-q \ number
Quality/robustness factor used to embed signature into image.
Overrides setting from signature file.
.TP
.BI \-s \ sfile
The signature file to embed into image. See
.B gen_koch_sig
(1) for a description of the file format. Mandatory parameter.
.TP
.BI \-v \ number
Verbosity level. 0 for quiet operation, higher numbers for more
output. Default value: 0.
.TP
.IR file
Input image in PGM format to sign (watermark). Default: standard input.
.PP
.SH OUTPUT
The signed (watermarked) image in PGM format is written to standard output
or, optionally, to
.I ofile.
.PP
Two coefficients of an 8x8 DCT block are selected at random to embed a
single signature bit.
.PP
.SH AUTHOR
Peter Meerwald. Email bug reports to pmeerw@cosy.sbg.ac.at.
.SH AVAILABILITY
The most recent released version of
.B wm_koch_e
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.
.SH "SEE ALSO"
.BR gen_koch_sig
(1),
.BR wm_koch_d
(1),
.BR cmp_koch_sig
(1)