wm_corvi_d(1)

NAME
wm_corvi_d - a program to extract a signature from the DWT residue of a watermarked image

SYNOPSIS
wm_corvi_d [ -a number ] [ -e number ] [ -f number ] [ -F ffile ] [ -g number ] [ -h ] [ -i ifile ]
[ -n number ] [ -o ofile ] [ -q number ] [ -v number ] -s sfile file

DESCRIPTION
wm_corvi_d is a program to extract a signature from the DWT residue of a watermarked image file. The cmp_corvi_sig program is used to test the extracted signature against the original signature. The input image is in PGM (portable graymap) format.

If file or ofile is not specified, then standard input or standard output is used.

gen_corvi_sig is used to generate a signature file, wm_corvi_e embeds the signature into an image.

Please refer to Marco Corvi's paper "Wavelet-based image watermarking for copyright protection", 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.

-e number
    Wavelet filtering method for forward transformation. Allows to override the setting in the signature file.

-f number
    Wavelet filter number. Allows to override the setting in the signature file.

-F ffile
    Wavelet filter definition file. Allows to override the setting in the signature file.

-g number
    Wavelet filtering method for inverse transformation. Allows to override the setting in the signature file.

-h  Print a help message.

-i ifile
    The original image.

-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.

-v number
    Verbosity level. Default value: 0.

-s sfile
    The signature file to embed into the input image. See gen_corvi_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 watermarked image in PGM format.

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

The output file has the following format:

CVSG
    Magic to identify file type.

number
    The length of the signature in bits.

number
    The alpha factor (embedding strength).

number
    The quantization/quality factor.

number
    The wavelet forward transform filtering method.

number
    The wavelet filter number.

file
    The wavelet filter definition file name.

number
    The wavelet inverse transform filtering method.

numbers
    The actual normal distributed signature values, one per line.

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

AVAILABILITY
The most recent released version of wm_corvi_d 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_corvi_sig (1), wm_corvi_e (1), wm_corvi_s (1), cmp_corvi_sig (1)