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author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Sun, 12 Aug 2007 13:14:34 +0200
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1 .\"
2 .\" wm_cox_d.1 - the *roff document processor man page source
3 .\"
4 .TH wm_cox_d 1 "98/07/05" "Watermarking, Version 1.0"
5 .SH NAME
6 .B wm_cox_d
7 \- a program to extract a signature from the DCT coefficients of a watermarked image
8 .SH SYNOPSIS
9 .B wm_cox_d
10 [
11 .BI \-a \ number
12 ]
13 [
14 .B \-h
15 ]
16 [
17 .BI \-i \ ifile
18 ]
19 [
20 .BI \-n \ number
21 ]
22 [
23 .BI \-o \ ofile
24 ]
25 [
26 .BI \-q \ number
27 ]
28 [
29 .BI \-v \ number
30 ]
31 .br
32 .BI \-s \ sfile
33 .I file
34 .SH DESCRIPTION
35 .B wm_cox_d
36 is a program to extract a signature from the DCT coefficients of the watermarked image
37 .I file.
38 The
39 .B cmp_cox_sig
40 program is used to test the extracted signature against the original signature.
41 The input image is in PGM (portable graymap) format.
42 .PP
43 If
44 .I file
45 or
46 .I ofile
47 is not specified, then standard input or standard output is
48 used.
49 .PP
50 .B gen_cox_sig
51 is used to generate a signature file,
52 .B wm_cox_e
53 embeds the signature into an image.
54 .PP
55 Please refer to Ingemar J. Cox's paper "Secure Spread Spectrum
56 Watermarking for Multimedia", 1995, to get an idea about the algorithm.
57 .PP
58 .SH OPTIONS
59 .TP
60 .BI \-a \ number
61 Alpha factor that determines embedding strength of the signature.
62 Allows to override the setting in the signature file.
63 .TP
64 .B \-h
65 Print a help message.
66 .TP
67 .BI \-i \ ifile
68 The original image.
69 .TP
70 .BI \-o \ ofile
71 Output watermarked image to the specified
72 .I file
73 instead of standard output.
74 .TP
75 .BI \-q \ number
76 Set quantization/quality factor. Overrides the setting in the signature
77 file.
78 .TP
79 .BI \-v \ number
80 Verbosity level. Default value: 0.
81 .TP
82 .BI \-s \ sfile
83 The signature file to embed into the input image. See
84 .B gen_cox_sig
85 (1) for a description of the file format. Mandatory parameter.
86 .IR file
87 Input image in PGM format to sign (watermark). Default: standard input.
88 .TP
89 .I
90 The watermarked image file in PGM format.
91 .PP
92 .SH OUTPUT
93 The signed (watermarked) image in PGM format is written to standard output
94 or ,optionally, to
95 .I ofile.
96 The embedding process may take some time on large images since the DCT
97 is performed on the whole image in one step (not block-wise).
98 .PP
99 .PP
100 The output file has the following format:
101 .TP
102 .B CXSG
103 Magic to identify file type.
104 .TP
105 .I number
106 The length of the signature in bits.
107 .TP
108 .I number
109 The alpha factor (embedding strength).
110 .TP
111 .I number
112 The quantization/quality factor.
113 .TP
114 .I numbers
115 The actual normal distributed signature values, one per line.
116 .PP
117 .SH AUTHOR
118 Peter Meerwald.
119 Email bug reports to pmeerw@cosy.sbg.ac.at.
120 .SH AVAILABILITY
121 The most recent released version of
122 .B wm_cox_d
123 is always available
124 at http://www.cosy.sbg.ac.at/~pmeerw/Watermarking or via anonymous ftp from ftp.cosy.sbg.ac.at in the
125 directory /pub/people/pmeerw/Watermarking.
126 .SH "SEE ALSO"
127 .BR gen_cox_sig
128 (1),
129 .BR wm_cox_e
130 (1),
131 .BR cmp_cox_sig
132 (1)

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