wm_koch_e(1)

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

SYNOPSIS
wm_koch_e [ -h ] [ -o ofile ] [ -q number ] [ -v number ] -s sfile file

DESCRIPTION
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 gen_koch_sig program. The wm_koch_d program is used to extract a signature from a signed (watermarked) image. The cmp_koch_sig program compares and tests the extracted signature against the original signature.

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.

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.

-o ofile
    Output signed (watermarked) image to ofile instead of standard output.

-q number
    Quality/robustness factor used to embed signature into image. Overrides setting from signature file.

-s sfile
    The signature file to embed into image. See gen_koch_sig (1) for a description of the file format. Mandatory parameter.

-v number
    Verbosity level. 0 for quiet operation, higher numbers for more output. Default value: 0.

file
    Input image in PGM format to sign (watermark). Default: standard input.

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

Two coefficients of an 8x8 DCT block are selected at random to embed a single signature bit.

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

AVAILABILITY
The most recent released version of 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.

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