wm_cox_e(1)

NAME
wm_cox_e - a program to embed a signature in the DCT coefficients of an image

SYNOPSIS
wm_cox_e [ -a number ] [ -h ] [ -o ofile ] [ -q number ] -s sfile file

DESCRIPTION
wm_cox_e is a program to embed a signature (watermark) from sfile into the DCT coefficients of an image file and output a signed (watermarked) image ofile. Both, input and output image, are in PGM (portable graymap) format.

If file or ofile is not specified, then standard input or standard output is used. The signature sfile is a mandatory parameter however.

gen_cox_sig is used to generate a signature file, wm_cox_d extracts a signature from a watermarked image and cmp_cox_sig allows to compare and test an extracted watermark against the original signature.

Please refer to Ingemar J. Cox's paper "Secure Spread Spectrum Watermarking for Multimedia", 1995, to get an idea about the algorithm.

OPTIONS

-a number
    Alpha factor that determines embedding strength of the signature. Allows to override the setting in the signature file.

-h  Print a help message.

-o ofile
    Output watermarked image to the specified file instead of standard output.

-q number
    Set quantization/quality factor. Overrides the setting in the signature file.

-s sfile
    The signature file to embed into the input image. See gen_cox_sig (1) for a description of the file format. Mandatory parameter. file Input image in PGM format to sign (watermark). Default: standard input.

file
    The input image in PGM format.

OUTPUT
The signed (watermarked) image in PGM format is written to standard output or, optionally, to 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).

The n largest coefficients are pulsed to embed the n bit watermark.

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

AVAILABILITY
The most recent released version of 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.

SEE ALSO
gen_cox_sig (1), wm_cox_d (1), cmp_cox_sig (1)