Raw Image (RGB) Multi Compositor

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
void usage(char *prog_name) {
  fprintf(
    stderr,
    "Usage: %s orig.raw compose1.raw compose2.raw ... out.raw", prog_name);
}
FILE **fopen_many(int n, char **name) {
  FILE **p = (FILE **) malloc(n * sizeof(FILE *));
  for (int i = 0; i < n; i++) {
    printf("Open #%d: %s\n", i, name[i]);
    p[i] = fopen(name[i], "rb");
  }
  return p;
}
unsigned char **read_many(FILE **in, int n) {
  unsigned char **p = (unsigned char **) malloc(n * sizeof(unsigned char *));
  for (int i = 0; i < n; i++) {
    p[i] = (unsigned char *) malloc(1 * sizeof(unsigned char));
    if (fscanf(in[i], "%c", p[i]) == EOF) return NULL;
  }
  return p;
}
void free_many(unsigned char **read, int n) {
  for (int i = 0; i < n; i++)
    free(read[i]);
  free(read);
}
void fclose_many(FILE **in, int n) {
  for (int i = 0; i < n; i++)
    fclose(in[i]);
}
int main(int argc, char **argv) {
  if (argc < 5) {
    usage(argv[0]);
    return EXIT_FAILURE;
  }
  FILE **in = fopen_many(argc - 2, argv + 1);
  FILE *out = fopen(argv[argc - 1], "wb");
  while (true) {
    unsigned char **read = read_many(in, argc - 2);
    if (read == NULL) break;
    unsigned char ou;
    double sum = 0;
    for (int i = 0; i < argc - 2; i++)
      sum += read[i][0];
    ou = 255 * read[0][0] / sum;
    fprintf(out, "%c", ou);
    free_many(read, argc - 2);
  }
  fclose_many(in, argc - 2);
  printf("Output: %s\n", argv[argc - 1]);
  fclose(out);
  return EXIT_SUCCESS;
}