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