.\"
.\" cmp_dct8x8.1 - the *roff document processor man page source
.\"
.TH cmp_dct8x8 1 "98/07/08" "Watermarking, Version 1.0"
.SH NAME
cmp_dct8x8 \- a program to create the difference image of the
8x8 DCT blocks of two PGM images
.SH SYNOPSIS
.B cmp_dct8x8
[
.B \-h
]
[
.BI \-m \ number
]
[
.BI \-o \ ofile
]
.BI \-i \ ifile
.I file
.SH DESCRIPTION
.B cmp_dct8x8
is a program to create the difference image of the 8x8 DCT blocks
(frequency domain) of two PGM (portable graymap) grayscale
images. To compare images in the spatial domain, either in
PPM (portable pixmap) format for RGB color images or in PGM (portable
graymap) format for grayscale images, use the
.B cmp_ppm
program or the
.B cmp_pgm
program, respectively.
.PP
If
.I file
or
.I ofile
is not specified, then standard input or standard output is
used.
.PP
.SH OPTIONS
.TP
.B \-h
Print a help message.
.TP
.BI \-i \ ifile
The original image. Mandatory.
.TP
.BI \-m \ number
Multiplication factor to magnify differences between the to
original and input image.
Default value: 16.
.TP
.BI \-o \ ofile
Output image file to contain the difference image in PGM format.
.TP
.I file
Input image that is compared against
.I ifile.
Default: standard input.
.SH OUTPUT
The difference image in PGM format is written to standard output or,
optionally, to
.I ofile.
.SH AUTHOR
Peter Meerwald. 
Email bug reports to pmeerw@cosy.sbg.ac.at.
.SH AVAILABILITY
The most recent released version of
.B cmp_dct8x8
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"
.B cmp_pgm
(1),
.B cmp_ppm
(1),
.B cmp_dct
(1)