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