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comparison Meerwald/wm_koch_e.c @ 0:be303a3f5ea8

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import
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Sun, 12 Aug 2007 13:14:34 +0200
parents
children f83ef905a63d
comparison
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-1:000000000000 0:be303a3f5ea8
1 #include "wm.h"
2 #include "dct.h"
3 #include "signature.h"
4 #include "coord.h"
5 #include "pgm.h"
6
7 char *progname;
8
9 void usage(void) {
10 fprintf(stderr, "usage: %s [-h] [-l n] [-o file] [-q n] [-v n] -s file file\n", progname);
11 fprintf(stderr, "\t-h\t\tprint usage\n");
12 fprintf(stderr, "\t-l n\t\tsignature robustness factor\n");
13 fprintf(stderr, "\t-o file\t\toutput (watermarked) file\n");
14 fprintf(stderr, "\t-q n\t\tquantization (JPEG quality) factor\n");
15 fprintf(stderr, "\t-s file\t\tsignature to embed in input image\n");
16 fprintf(stderr, "\t-v n\t\tverbosity level\n");
17 exit(0);
18 }
19
20 int main(int argc, char *argv[]) {
21
22 FILE *in = stdin;
23 FILE *out = stdout;
24 FILE *sig = NULL;
25
26 char signature_name[MAXPATHLEN];
27 char input_name[MAXPATHLEN] = "(stdin)";
28 char output_name[MAXPATHLEN] = "(stdout)";
29
30 int i;
31 int j;
32 int c;
33 int n;
34 int x;
35 int y;
36
37 int seed;
38 int verbose = 0;
39
40 int rows, cols, format;
41 gray maxval;
42 int row, col;
43
44 int quantization = 0;
45 double quality = 0.0;
46
47 struct coords *coords;
48
49 gray **image;
50 double **dcts;
51
52 progname = argv[0];
53
54 pgm_init(&argc, argv); wm_init();
55
56 while ((c = getopt(argc, argv, "h?i:l:o:q:s:v:")) != EOF) {
57 switch (c) {
58 case 'h':
59 case '?':
60 usage();
61 break;
62 case 'l':
63 quality = atof(optarg);
64 if (quality <= 0.0) {
65 fprintf(stderr, "%s: signature strength factor %f out of range\n", progname, quality);
66 exit(1);
67 }
68 break;
69 case 'o':
70 if ((out = fopen(optarg, "wb")) == NULL) {
71 fprintf(stderr, "%s: unable to open output file %s\n", progname, optarg);
72 exit(1);
73 }
74 strcpy(output_name, optarg);
75 break;
76 case 'q':
77 quantization = atoi(optarg);
78 if (quantization <= 0 || quantization > 100) {
79 fprintf(stderr, "%s: quantization factor %d out of range\n", progname, quantization);
80 exit(1);
81 }
82 break;
83 case 's':
84 if ((sig = fopen(optarg, "r")) == NULL) {
85 fprintf(stderr, "%s: unable to open signature file %s\n", progname, optarg);
86 exit(1);
87 }
88 strcpy(signature_name, optarg);
89 break;
90 case 'v':
91 verbose = atoi(optarg);
92 if (verbose < 0) {
93 fprintf(stderr, "%s: verbosity level %d out of range\n", progname, verbose);
94 exit(1);
95 }
96 break;
97 }
98 }
99
100 argc -= optind;
101 argv += optind;
102
103 if (argc > 1) {
104 usage();
105 exit(1);
106 }
107
108 if (argc == 1 && *argv[0] != '-')
109 if ((in = fopen(argv[0], "rb")) == NULL) {
110 fprintf(stderr, "%s: unable to open input file %s\n", progname, argv[0]);
111 exit(1);
112 }
113 else
114 strcpy(input_name, argv[0]);
115
116 if (sig) {
117 char line[128];
118 fgets(line, sizeof(line), sig);
119 if (strspn(line, "KCSG") >= 4) {
120 fscanf(sig, "%d\n", &nbit_signature);
121 if (quality == 0.0)
122 fscanf(sig, "%lf\n", &quality);
123 else
124 fscanf(sig, "%*lf\n");
125 if (quantization == 0)
126 fscanf(sig, "%d\n", &quantization);
127 else
128 fscanf(sig, "%*d\n");
129 fscanf(sig, "%d\n", &seed);
130 n_signature = NBITSTOBYTES(nbit_signature);
131 fread(signature, sizeof(char), n_signature, sig);
132 fscanf(sig, "\n");
133 srandom(seed);
134 }
135 else {
136 fprintf(stderr, "%s: invalid signature file %s\n", progname, signature_name);
137 exit(1);
138 }
139 fclose(sig);
140 }
141 else {
142 fprintf(stderr, "%s: signature file not specified, use -s file option\n", progname);
143 exit(1);
144 }
145
146 pgm_readpgminit(in, &cols, &rows, &maxval, &format);
147
148 if (cols % NJPEG) {
149 fprintf(stderr, "%s: image width %d not a multiple of %d\n", progname, cols, NJPEG);
150 exit(1);
151 }
152
153 if (rows % NJPEG) {
154 fprintf(stderr, "%s: image height %d not a multiple of %d\n", progname, rows, NJPEG);
155 exit(1);
156 }
157
158 if ((cols * rows) / (NJPEG * NJPEG) < nbit_signature) {
159 fprintf(stderr, "%s: image not large enough to embed %d bits of signature\n", progname, nbit_signature);
160 exit(1);
161 }
162
163 init_dct_8x8();
164 init_quantum_JPEG_lumin(quantization);
165
166 dcts = alloc_coeffs_8x8();
167
168 if ((coords = alloc_coords(nbit_signature)) == NULL) {
169 fprintf(stderr, "%s: unable to allocate memory\n", progname);
170 exit(1);
171 }
172
173 image = pgm_allocarray(cols, rows);
174
175 for (row = 0; row < rows; row++)
176 pgm_readpgmrow(in, image[row], cols, maxval, format);
177
178 fclose(in);
179
180 // embedding signature bits by modifying two coefficient relationship,
181 // one bit for each block
182 n = 0;
183 while (n < nbit_signature) {
184 int xb;
185 int yb;
186 int c1, c2;
187 double v1, v2;
188 double w1, w2;
189 double diff, abs_diff;
190
191 // randomly select a block, check to get distinct blocks
192 // (don't watermark a block twice)
193 do {
194 xb = random() % (cols / NJPEG);
195 yb = random() % (rows / NJPEG);
196 } while (add_coord(coords, xb, yb) < 0);
197
198 // do the forward 8x8 DCT of that block
199 fdct_block_8x8(image, xb * NJPEG, yb * NJPEG, dcts);
200
201 // randomly select two distinct coefficients from block
202 // only accept coefficients in the middle frequency range
203 do {
204 c1 = (random() % (NJPEG * NJPEG - 2)) + 1;
205 c2 = (random() % (NJPEG * NJPEG - 2)) + 1;
206 } while (c1 == c2 || !is_middle_frequency_coeff_8x8(c1) || !is_middle_frequency_coeff_8x8(c2));
207
208 // quantize block according to quantization quality parameter
209 quantize_8x8(dcts);
210
211 if (verbose > 0)
212 fprintf(stderr, "%d: quantized DCT block (x %d/y %d), modifying (x %d/y %d), (x %d/y %d) for %s\n", n, xb * NJPEG, yb * NJPEG, c1 % NJPEG, c1 / NJPEG, c2 % NJPEG, c2 / NJPEG, get_signature_bit(n) ? "HIGH" : "LOW");
213 if (verbose > 5)
214 print_coeffs_8x8(dcts);
215
216 v1 = dcts[c1 / NJPEG][c1 % NJPEG];
217 v2 = dcts[c2 / NJPEG][c2 % NJPEG];
218
219 diff = fabs(v1) - fabs(v2);
220 abs_diff = (fabs(diff) + quality) / 2.0;
221
222 // modify coefficient's relationship to embed signature bit
223 // using mean square error to minimize error
224 if (get_signature_bit(n)) {
225 if (diff < quality) {
226 // we have to impose the relationship, does not occur naturally
227 w1 = (v1 > 0.0) ? (v1 + abs_diff) : (v1 - abs_diff);
228 w2 = (v2 > 0.0) ? (v2 - abs_diff) : (v2 + abs_diff);
229 }
230 else {
231 w1 = v1;
232 w2 = v2;
233 }
234 }
235 else {
236 if (diff > -quality) {
237 // force the relationship
238 w1 = (v1 > 0.0) ? (v1 - abs_diff) : (v1 + abs_diff);
239 w2 = (v2 > 0.0) ? (v2 + abs_diff) : (v2 - abs_diff);
240 }
241 else {
242 w1 = v1;
243 w2 = v2;
244 }
245 }
246
247 if (verbose > 1)
248 fprintf(stderr, " %f -> %f, %f -> %f\n", v1, w1, v2, w2);
249
250 // put the changed coefficients back to black
251 dcts[c1 / NJPEG][c1 % NJPEG] = w1;
252 dcts[c2 / NJPEG][c2 % NJPEG] = w2;
253
254 // the obvious :-)
255 dequantize_8x8(dcts);
256
257 // do the inverse DCT on the modified 8x8 block
258 idct_block_8x8(dcts, image, xb * NJPEG, yb * NJPEG);
259
260 n++;
261 }
262
263 free_coeffs(dcts);
264
265 pgm_writepgminit(out, cols, rows, maxval, 0);
266 for (row = 0; row < rows; row++)
267 pgm_writepgmrow(out, image[row], cols, maxval, 0);
268
269 fclose(out);
270
271 pgm_freearray(image, rows);
272
273 exit(0);
274 }

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