--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Meerwald-dir/wm_cox_d.c	Fri Dec 20 13:08:59 2024 +0100
@@ -0,0 +1,228 @@
+#include "wm.h"
+#include "dct.h"
+#include "netpbm/pgm.h"
+#include "sort.h"
+
+char *progname;
+
+void usage(void) {
+  fprintf(stderr, "usage: %s [-a n] [-h] [-n n] [-o file] [-s file] [-v n] -i file file\n\n", progname);
+  fprintf(stderr, "\t-a n\t\talpha factor (default 0.3)\n");
+  fprintf(stderr, "\t-h\t\tprint usage\n");
+  fprintf(stderr, "\t-i file\t\toriginal image file\n");
+  fprintf(stderr, "\t-n n\t\twatermark length (default 100)\n");
+  fprintf(stderr, "\t-o file\t\textracted signature file\n");
+  fprintf(stderr, "\t-s file\t\toriginal signature file\n");
+  fprintf(stderr, "\t-v n\t\tverbosity level\n");
+  exit(0);
+}
+
+int main(int argc, char *argv[]) {
+
+  FILE *in = stdin;
+  FILE *out = stdout;
+  FILE *orig = NULL;
+  FILE *sig = NULL;
+
+  gray **input_image;
+  gray **orig_image;
+
+  char signature_name[MAXPATHLEN];
+  char output_name[MAXPATHLEN] = "(stdout)";
+  char input_name[MAXPATHLEN] = "(stdin)";
+  char orig_name[MAXPATHLEN];
+
+  int c;
+  int i, j;
+  int n = 100;
+
+  double a = 0.3;
+
+  int warn_n = 1;
+  int warn_a = 1;
+
+  int in_rows, in_cols, in_format;
+  gray in_maxval;
+  int orig_rows, orig_cols, orig_format;
+  gray orig_maxval;
+  int rows, cols;
+  int row;
+
+  double threshold;
+  double *largest;
+
+  double **input_dcts;
+  double **orig_dcts;
+  
+  int verbose = 0;
+
+  progname = argv[0];
+
+  pgm_init(&argc, argv); wm_init2();
+
+  while ((c = getopt(argc, argv, "h?i:n:o:s:v:")) != EOF) {
+    switch (c) {
+      case 'a':
+        a = atof(optarg);
+        if (a <= 0.0) {
+          fprintf(stderr, "%s: alpha factor %f out of range\n", progname, a);
+          exit(1);
+        }
+        warn_a = 0;
+        break;
+      case 'h':
+      case '?':
+        usage();
+        break;
+      case 'i':
+        if ((orig = fopen(optarg, "rb")) == NULL) {
+          fprintf(stderr, "%s: unable to open original image file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(orig_name, optarg);
+        break;
+      case 'n':
+        n = atoi(optarg);
+        if (n < 1 || n > 1000) {
+          fprintf(stderr, "%s: watermark length %d out of range\n", progname, n);
+          exit(1);
+        }
+        warn_n = 0;
+        break;
+      case 'o':
+        if ((out = fopen(optarg, "w")) == NULL) {
+          fprintf(stderr, "%s: unable to open output file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(output_name, optarg);
+        break;
+      case 's':
+        if ((sig = fopen(optarg, "r")) == NULL) {
+          fprintf(stderr, "%s: unable to open signature file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(signature_name, optarg);
+        break;
+      case 'v':
+        verbose = atoi(optarg);
+        if (verbose < 0) {
+          fprintf(stderr, "%s: verbosity level %d out of range\n", progname, verbose);
+          exit(1);
+        }
+        break;
+    }
+  }
+
+  argc -= optind;
+  argv += optind;
+
+  if (argc > 1) {
+    usage();
+    exit(1);
+  }
+
+  if (argc == 1 && *argv[0] != '-') {
+    if ((in = fopen(argv[0], "rb")) == NULL) {
+      fprintf(stderr, "%s: unable to open input file %s\n", progname, argv[0]);
+      exit(1);
+    }
+    else
+      strcpy(input_name, argv[0]);
+  }
+  
+  if (!orig) {
+    fprintf(stderr, "%s: original image file not specified, use -i file option\n", progname);
+    exit(1);
+  }
+
+  if (sig) {
+    char line[32];
+    fgets(line, sizeof(line), sig);
+    if (strspn(line, "CXSG") >= 4) {
+      fscanf(sig, "%d\n", &n);
+      if (warn_a)
+        fscanf(sig, "%lf\n", &a);
+      else
+        fscanf(sig, "%*f\n");
+      fscanf(sig, "%*f\n");
+      fscanf(sig, "%*f\n");
+    }
+    else {
+      fprintf(stderr, "%s: invalid signature file %s\n", progname, signature_name);
+      exit(1);
+    }
+    fclose(sig);
+  }
+  else {
+    if (warn_a)
+      fprintf(stderr, "%s: warning - alpha factor not specified, using default %f\n", progname, a);
+    if (warn_n)
+      fprintf(stderr, "%s: warning - watermark length not specified, using default %d\n", progname, n);
+  }
+
+  pgm_readpgminit(in, &in_cols, &in_rows, &in_maxval, &in_format);
+  pgm_readpgminit(orig, &orig_cols, &orig_rows, &orig_maxval, &orig_format);
+
+  if (in_cols != orig_cols || in_rows != orig_rows) {
+    fprintf(stderr, "%s: input image %s does not match dimensions of original image %s\n", progname, input_name, orig_name);
+    exit(1);
+  }
+
+  cols = in_cols;
+  rows = in_rows;
+
+  init_dct_NxN(cols, rows);
+
+  input_image = pgm_allocarray(in_cols, in_rows);
+
+  orig_image = pgm_allocarray(orig_cols, orig_rows);
+
+  for (row = 0; row < in_rows; row++)
+    pgm_readpgmrow(in, input_image[row], in_cols, in_maxval, in_format);
+
+  fclose(in);
+
+  for (row = 0; row < orig_rows; row++)
+    pgm_readpgmrow(orig, orig_image[row], orig_cols, orig_maxval, orig_format);
+
+  fclose(orig);
+
+  input_dcts = alloc_coeffs(cols, rows);
+  orig_dcts = alloc_coeffs(cols, rows);
+
+  fdct_NxN(input_image, input_dcts);
+  fdct_NxN(orig_image, orig_dcts);
+
+  largest = malloc((n + 1) * sizeof(double));
+  select_largest_coeffs(orig_dcts[0], cols * rows, n+1, largest);
+  threshold = largest[0];
+  free(largest);
+
+  fprintf(out, "CXWM\n");
+  fprintf(out, "%d\n", n);
+
+  j = 0;
+  for (i = 0; i < n; i++) {
+    double d, o, p;
+
+    while ((o = orig_dcts[j / cols][j % cols]) < threshold) j++;
+
+    p = input_dcts[j / cols][j % cols]; 
+ 
+    d = (p / o - 1.0) / a;
+    if (verbose >= 1)
+      fprintf(stderr, "input %f orig %f alpha %f d %f\n", p, o, a, d);
+    fprintf(out, "%f\n", d);
+    j++;
+  }
+
+  fclose(out);
+
+  free_coeffs(input_dcts);
+  free_coeffs(orig_dcts);
+
+  pgm_freearray(input_image, rows);
+  pgm_freearray(orig_image, rows);
+
+  exit(0);
+}