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| author | Peter Meerwald-Stadler <pmeerw@pmeerw.net> |
|---|---|
| date | Fri, 20 Dec 2024 13:08:59 +0100 |
| parents | Meerwald/wm_koch_d.1@be303a3f5ea8 |
| children |
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| 23:71dd4b96221b | 24:9f20bce6184e |
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| 1 .\" | |
| 2 .\" wm_koch_d.1 - the *roff document processor man page source | |
| 3 .\" | |
| 4 .TH wm_koch_d 1 "98/07/05" "Watermarking, Version 1.0" | |
| 5 .SH NAME | |
| 6 .B wm_koch_d | |
| 7 \- a program to extract signature bits that have been embedded into | |
| 8 the DCT coefficients of an image | |
| 9 .SH SYNOPSIS | |
| 10 .B wm_koch_d | |
| 11 [ | |
| 12 .B \-h | |
| 13 ] | |
| 14 [ | |
| 15 .BI \-o \ ofile | |
| 16 ] | |
| 17 [ | |
| 18 .BI \-q \ number | |
| 19 ] | |
| 20 [ | |
| 21 .BI \-v \ number | |
| 22 ] | |
| 23 .BI \-s \ sfile | |
| 24 .IR file | |
| 25 .SH DESCRIPTION | |
| 26 .B wm_koch_d | |
| 27 is a program to extract signature bits from the 8x8 DCT coefficients of | |
| 28 an image, embedded with the | |
| 29 .B wm_koch_e | |
| 30 watermarking program. | |
| 31 .B cmp_koch_sig | |
| 32 program compares and tests the extracted signature against the original signature. | |
| 33 .PP | |
| 34 The input image is in PGM (portable graymap) format. | |
| 35 .PP | |
| 36 If | |
| 37 .I file | |
| 38 or | |
| 39 .I ofile | |
| 40 is not specified, then standard input or standard output is | |
| 41 used. The signature | |
| 42 .I sfile | |
| 43 is a mandatory parameter however. | |
| 44 .PP | |
| 45 Please refer to E. Koch's paper "Towards Robust and Hidden | |
| 46 Image Copyright", 1995, to get an idea about the algorithm. | |
| 47 .PP | |
| 48 .SH OPTIONS | |
| 49 .TP | |
| 50 .B \-h | |
| 51 Print a help message. | |
| 52 .TP | |
| 53 .BI \-o \ ofile | |
| 54 Output the extracted signature to | |
| 55 .I ofile | |
| 56 instead of standard output. | |
| 57 .TP | |
| 58 .BI \-q \ number | |
| 59 Quality/robustness factor used to extract the signature. | |
| 60 Overrides setting from signature file. | |
| 61 .TP | |
| 62 .BI \-s \ sfile | |
| 63 The original signature file. See | |
| 64 .B gen_koch_sig | |
| 65 (1) for a description of the file format. Mandatory parameter. | |
| 66 .BI \-v \ number | |
| 67 Verbosity level. 0 for quiet operation, higher numbers for more | |
| 68 output. Default value: 0. | |
| 69 .TP | |
| 70 .IR file | |
| 71 Signed (watermarked) input image in PGM format. Default: standard input. | |
| 72 .PP | |
| 73 .SH OUTPUT | |
| 74 The extracted signature is written to standard output | |
| 75 or, optionally, to | |
| 76 .I ofile. | |
| 77 .PP | |
| 78 The extraction algorithm examines the relationship between two random | |
| 79 coefficients of randomly selected 8x8 DCT blocks to reconstruct the | |
| 80 signature bits. | |
| 81 .PP | |
| 82 The output file has the following format: | |
| 83 .TP | |
| 84 .B KCSG | |
| 85 Magic to identify file type. | |
| 86 .TP | |
| 87 .I number | |
| 88 The length of the signature in bits. | |
| 89 .TP | |
| 90 .I number | |
| 91 The quality/robustness factor. | |
| 92 .TP | |
| 93 .I number | |
| 94 The seed value for the pseudo-random number generator. | |
| 95 .TP | |
| 96 .I string | |
| 97 The actual signature bytes. | |
| 98 .PP | |
| 99 .SH AUTHOR | |
| 100 Peter Meerwald. | |
| 101 Email bug reports to pmeerw@cosy.sbg.ac.at. | |
| 102 .SH AVAILABILITY | |
| 103 The most recent released version of | |
| 104 .B wm_koch_d | |
| 105 is always available | |
| 106 at http://www.cosy.sbg.ac.at/~pmeerw/Watermarking or via anonymous ftp from ftp.cosy.sbg.ac.at in the | |
| 107 directory /pub/people/pmeerw/Watermarking. | |
| 108 .SH "SEE ALSO" | |
| 109 .BR gen_koch_sig | |
| 110 (1), | |
| 111 .BR wm_koch_e | |
| 112 (1), | |
| 113 .BR cmp_koch_sig | |
| 114 (1) |