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.\" wm_cox_e.1 - the *roff document processor man page source
.\"
.TH wm_cox_e 1 "98/07/01" "Watermarking, Version 1.0"
.SH NAME
.B wm_cox_e
\- a program to embed a signature in the DCT coefficients of an image
.SH SYNOPSIS
.B wm_cox_e
[
.BI \-a \ number
]
[
.B \-h
]
[
.BI \-o \ ofile
]
[
.BI \-q \ number
]
.BI \-s \ sfile
.I file
.SH DESCRIPTION
.B wm_cox_e
is a program to embed a signature (watermark) from
.I sfile
into the DCT coefficients of an image
.I file
and output a signed (watermarked) image
.I ofile.
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
.B gen_cox_sig
is used to generate a signature file,
.B wm_cox_d
extracts a signature from a watermarked image and
.B cmp_cox_sig
allows to compare and test an extracted watermark against the original
signature.
.PP
Please refer to Ingemar J. Cox's paper "Secure Spread Spectrum
Watermarking for Multimedia", 1995, to get an idea about the algorithm.
.PP
.SH OPTIONS
.TP
.BI \-a \ number
Alpha factor that determines embedding strength of the signature.
Allows to override the setting in the signature file.
.TP
.B \-h
Print a help message.
.TP
.BI \-o \ ofile
Output watermarked image to the specified
.I file
instead of standard output.
.TP
.BI \-q \ number
Set quantization/quality factor. Overrides the setting in the signature
file.
.TP
.BI \-s \ sfile
The signature file to embed into the input image. See
.B gen_cox_sig
(1) for a description of the file format. Mandatory parameter.
.IR file
Input image in PGM format to sign (watermark). Default: standard input.
.TP
.I file
The input image in PGM format.
.PP
.SH OUTPUT
The signed (watermarked) image in PGM format is written to standard output
or, optionally, to
.I ofile.
The embedding process may take some time on large images since the DCT
is performed on the whole image in one step (not block-wise).
.PP
The
.I n
largest coefficients are pulsed to embed the
.I n
bit watermark.
.PP
.SH AUTHOR
Peter Meerwald. Email bug reports to pmeerw@cosy.sbg.ac.at.
.SH AVAILABILITY
The most recent released version of
.B wm_cox_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_cox_sig
(1),
.BR wm_cox_d
(1),
.BR cmp_cox_sig
(1)