raw12MP.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define N (32768+18580480)

int main(int argc, char* argv[])
{
  FILE *src;
  char c, *buf;
  assert( argc == 2 );
  assert( (src = fopen(argv[1], "rb")) );
  assert( (buf = malloc(N)) );
  assert( buf == memcpy(buf, "BRCM", 4) );
 
  while (1)
  {
    while (!feof(src) && fgetc(src) != 'B')  {}
    if (feof(src))  return 1;

    if ((c = fgetc(src)) == 'R')
      if ((c = fgetc(src)) == 'C')
        if ((c = fgetc(src)) == 'M')
        {
          assert(1 == fread(buf+4, N-4, 1, src));
          assert(1 == fwrite(buf, N, 1, stdout));
          return 0; 
        }

    assert(c == ungetc(c, src));
  }
}

https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=286001&p=1730777#p1730777

🍓 raspistill -r -md 3 -w 4056 -h 3040 -o tst.jpg
🍓 ./raw12MP tst.jpg > tst.raw
🍓 dcraw tst.raw 
🍓 file tst.ppm
tst.ppm: Netpbm image data, size = 4056 x 3040, rawbits, pixmap
🍓