--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Meerwald-dir/cmp_pgm.c	Fri Dec 20 13:08:59 2024 +0100
@@ -0,0 +1,202 @@
+#include "wm.h"
+#include "netpbm/pgm.h"
+
+char *progname;
+
+void usage(void) {
+  fprintf(stderr, "usage: %s [-C] [-h] [-m n] [-o file] [-pP] -i file file\n\n", progname);
+  fprintf(stderr, "\t-C\t\tprint PSNR value only\n");
+  fprintf(stderr, "\t-h\t\tprint usage\n");
+  fprintf(stderr, "\t-i file\t\toriginal image file\n");
+  fprintf(stderr, "\t-m n\t\tmultiplication factor (default auto)\n");
+  fprintf(stderr, "\t-o file\t\toutput file for difference image\n");
+  fprintf(stderr, "\t-p\t\tprint PSNR, RMS and MSE\n");
+  fprintf(stderr, "\t-P\t\tonly print PSNR, RMS and MSE, no difference image\n");
+  exit(0);
+}
+
+int main(int argc, char *argv[]) {
+
+  FILE *in = stdin;
+  FILE *out = stdout;
+  FILE *orig = NULL;
+
+  gray **input_image;
+  gray **orig_image;
+
+  char output_name[MAXPATHLEN] = "(stdout)";
+  char input_name[MAXPATHLEN] = "(stdin)";
+  char orig_name[MAXPATHLEN];
+
+  int in_cols, in_rows, in_format;
+  gray in_maxval;
+  int orig_cols, orig_rows, orig_format;
+  gray orig_maxval;
+  int cols, rows;
+  gray maxval;
+  int col, row;
+
+  int c;
+
+  int m = 0;
+  int min, max;
+
+  int print_psnr = 0;
+  int print_psnr_only = 0;
+  int print_psnr_value_only = 0;
+  double error = 0.0;
+
+  progname = argv[0];
+
+  pgm_init(&argc, argv); wm_init();
+
+  while ((c = getopt(argc, argv, "h?i:m:o:pPC")) != EOF) {
+    switch (c) {
+      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 'm':
+        m = atoi(optarg);
+        if (m <= 0) {
+          fprintf(stderr, "%s: multiplication factor %d out of range\n", progname, m);
+          exit(1);
+        }
+        break;
+      case 'o':
+        if ((out = fopen(optarg, "wb")) == NULL) {
+          fprintf(stderr, "%s: unable to open output file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(output_name, optarg);
+        break;
+      case 'p':
+        print_psnr = 1;
+        break;
+      case 'P':
+        print_psnr_only = 1;
+        break;
+      case 'C':
+        print_psnr_value_only = 1;
+        print_psnr_only = 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);
+  }
+
+  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;
+  maxval = in_maxval;
+
+  input_image = pgm_allocarray(cols, rows);
+  orig_image = pgm_allocarray(cols, rows);
+
+  for (row = 0; row < rows; row++) {
+      pgm_readpgmrow(in, input_image[row], cols, in_maxval, in_format);
+      pgm_readpgmrow(orig, orig_image[row], cols, orig_maxval, orig_format);
+  }
+
+  fclose(in);
+  fclose(orig);
+
+  min = max = abs(input_image[0][0] - orig_image[0][0]);
+
+  for (row = 0; row < rows; row++) {
+    gray *pi = input_image[row];
+    gray *po = orig_image[row];
+
+    for (col = 0; col < cols; col++) {
+      int diff = abs(*pi - *po);
+      error += sqr(diff);
+      if (diff < min) min = diff;
+      if (diff > max) max = diff;
+
+      pi++;
+      po++;
+    }
+  }
+
+  for (row = 0; row < rows; row++) {
+    gray *pi = input_image[row];
+    gray *po = orig_image[row];
+
+    for (col = 0; col < cols; col++) {
+      int diff = abs(*pi - *po);
+      if (m > 0)
+        *pi = PIXELRANGE(diff * m);
+      else
+        *pi = PIXELRANGE((double) (diff - min) / (double) (max - min) * maxval);
+
+      pi++;
+      po++;
+    }
+  }
+
+  if (!print_psnr_only) {
+    pgm_writepgminit(out, cols, rows, maxval, 0);
+    for (row = 0; row < rows; row++)
+      pgm_writepgmrow(out, input_image[row], cols, maxval, 0);
+
+    fclose(out);
+  }
+
+  pgm_freearray(input_image, rows);
+  pgm_freearray(orig_image, rows);
+
+  if (print_psnr || print_psnr_only) {
+    double mse = error / (double) (cols * rows);
+    double rmse = sqrt(mse);
+    double psnr = 20.0 * log(255.0 / rmse) / log(10.0);
+    FILE *print = print_psnr_only ? out : stderr;
+    if (!print_psnr_value_only) {
+      if (mse > 0.0) 
+        fprintf(print, "PSNR: %lf dB\n", psnr);
+      else 
+        fprintf(print, "PSNR: inf\n");
+      fprintf(print, "RMSE: %lf\n", rmse);
+      fprintf(print, "MSE: %lf\n", mse);
+      fprintf(print, "dmin, dmax: %d, %d\n", min, max);
+    }
+    else
+      fprintf(print, "%lf\n", mse > 0.0 ? psnr : 100.0);
+  }
+
+  exit(0);
+}