Nikon Electronic File (NEF) file format description

7. References

• DCRaw, the reference open source software to decode RAW formats, by Dave Coffin.
• EXIF organisation.
• Jpeg file format, ITU-t81 and ISO/IEC IS 10918-1 standard.
• TIFF resources. Adobe.
• Exiftool Nikon tags.
• DeNEF - Nikon D1 NEF image file decoder. local
• Formats d'image - RAW. C. Rousseau (French)
• Open source photography, NEF
• Is the Nikon D70 NEF (RAW) format truly lossless?

8. Samples

9. White Balance encryption

See ExifTool Nikon tags : 0x1d (serial), 0xa7 (shuttercount), 0x97 (colorbalance)

(from DCraw v8.89)

ushort CLASS sget2 (uchar *s)
{
  if (order == 0x4949)		/* "II" means little-endian */
    return s[0] | s[1] << 8;
  else				/* "MM" means big-endian */
    return s[0] << 8 | s[1];
}

void CLASS parse_makernote (int base, int uptag) {
  static const uchar xlat[2][256] = {
  { 0xc1,0xbf,0x6d,0x0d,0x59,0xc5,0x13,0x9d,0x83,0x61,0x6b,0x4f,0xc7,0x7f,0x3d,0x3d,
    0x53,0x59,0xe3,0xc7,0xe9,0x2f,0x95,0xa7,0x95,0x1f,0xdf,0x7f,0x2b,0x29,0xc7,0x0d,
    0xdf,0x07,0xef,0x71,0x89,0x3d,0x13,0x3d,0x3b,0x13,0xfb,0x0d,0x89,0xc1,0x65,0x1f,
    0xb3,0x0d,0x6b,0x29,0xe3,0xfb,0xef,0xa3,0x6b,0x47,0x7f,0x95,0x35,0xa7,0x47,0x4f,
    0xc7,0xf1,0x59,0x95,0x35,0x11,0x29,0x61,0xf1,0x3d,0xb3,0x2b,0x0d,0x43,0x89,0xc1,
    0x9d,0x9d,0x89,0x65,0xf1,0xe9,0xdf,0xbf,0x3d,0x7f,0x53,0x97,0xe5,0xe9,0x95,0x17,
    0x1d,0x3d,0x8b,0xfb,0xc7,0xe3,0x67,0xa7,0x07,0xf1,0x71,0xa7,0x53,0xb5,0x29,0x89,
    0xe5,0x2b,0xa7,0x17,0x29,0xe9,0x4f,0xc5,0x65,0x6d,0x6b,0xef,0x0d,0x89,0x49,0x2f,
    0xb3,0x43,0x53,0x65,0x1d,0x49,0xa3,0x13,0x89,0x59,0xef,0x6b,0xef,0x65,0x1d,0x0b,
    0x59,0x13,0xe3,0x4f,0x9d,0xb3,0x29,0x43,0x2b,0x07,0x1d,0x95,0x59,0x59,0x47,0xfb,
    0xe5,0xe9,0x61,0x47,0x2f,0x35,0x7f,0x17,0x7f,0xef,0x7f,0x95,0x95,0x71,0xd3,0xa3,
    0x0b,0x71,0xa3,0xad,0x0b,0x3b,0xb5,0xfb,0xa3,0xbf,0x4f,0x83,0x1d,0xad,0xe9,0x2f,
    0x71,0x65,0xa3,0xe5,0x07,0x35,0x3d,0x0d,0xb5,0xe9,0xe5,0x47,0x3b,0x9d,0xef,0x35,
    0xa3,0xbf,0xb3,0xdf,0x53,0xd3,0x97,0x53,0x49,0x71,0x07,0x35,0x61,0x71,0x2f,0x43,
    0x2f,0x11,0xdf,0x17,0x97,0xfb,0x95,0x3b,0x7f,0x6b,0xd3,0x25,0xbf,0xad,0xc7,0xc5,
    0xc5,0xb5,0x8b,0xef,0x2f,0xd3,0x07,0x6b,0x25,0x49,0x95,0x25,0x49,0x6d,0x71,0xc7 },
    
  { 0xa7,0xbc,0xc9,0xad,0x91,0xdf,0x85,0xe5,0xd4,0x78,0xd5,0x17,0x46,0x7c,0x29,0x4c,
    0x4d,0x03,0xe9,0x25,0x68,0x11,0x86,0xb3,0xbd,0xf7,0x6f,0x61,0x22,0xa2,0x26,0x34,
    0x2a,0xbe,0x1e,0x46,0x14,0x68,0x9d,0x44,0x18,0xc2,0x40,0xf4,0x7e,0x5f,0x1b,0xad,
    0x0b,0x94,0xb6,0x67,0xb4,0x0b,0xe1,0xea,0x95,0x9c,0x66,0xdc,0xe7,0x5d,0x6c,0x05,
    0xda,0xd5,0xdf,0x7a,0xef,0xf6,0xdb,0x1f,0x82,0x4c,0xc0,0x68,0x47,0xa1,0xbd,0xee,
    0x39,0x50,0x56,0x4a,0xdd,0xdf,0xa5,0xf8,0xc6,0xda,0xca,0x90,0xca,0x01,0x42,0x9d,
    0x8b,0x0c,0x73,0x43,0x75,0x05,0x94,0xde,0x24,0xb3,0x80,0x34,0xe5,0x2c,0xdc,0x9b,
    0x3f,0xca,0x33,0x45,0xd0,0xdb,0x5f,0xf5,0x52,0xc3,0x21,0xda,0xe2,0x22,0x72,0x6b,
    0x3e,0xd0,0x5b,0xa8,0x87,0x8c,0x06,0x5d,0x0f,0xdd,0x09,0x19,0x93,0xd0,0xb9,0xfc,
    0x8b,0x0f,0x84,0x60,0x33,0x1c,0x9b,0x45,0xf1,0xf0,0xa3,0x94,0x3a,0x12,0x77,0x33,
    0x4d,0x44,0x78,0x28,0x3c,0x9e,0xfd,0x65,0x57,0x16,0x94,0x6b,0xfb,0x59,0xd0,0xc8,
    0x22,0x36,0xdb,0xd2,0x63,0x98,0x43,0xa1,0x04,0x87,0x86,0xf7,0xa6,0x26,0xbb,0xd6,
    0x59,0x4d,0xbf,0x6a,0x2e,0xaa,0x2b,0xef,0xe6,0x78,0xb6,0x4e,0xe0,0x2f,0xdc,0x7c,
    0xbe,0x57,0x19,0x32,0x7e,0x2a,0xd0,0xb8,0xba,0x29,0x00,0x3c,0x52,0x7d,0xa8,0x49,
    0x3b,0x2d,0xeb,0x25,0x49,0xfa,0xa3,0xaa,0x39,0xa7,0xc5,0xa7,0x50,0x11,0x36,0xfb,
    0xc6,0x67,0x4a,0xf5,0xa5,0x12,0x65,0x7e,0xb0,0xdf,0xaf,0x4e,0xb3,0x61,0x7f,0x2f } };

  unsigned ver97=0, serial=0, i, wbi=0, wb[4]={0,0,0,0};
  uchar buf97[324], ci, cj, ck;

    if (tag == 0x97) {
      for (i=0; i < 4; i++)
        ver97 = ver97 * 10 + fgetc(ifp)-'0';
      switch (ver97) {
      case 100: // version < 200 is not encrypted
	      fseek (ifp, 68, SEEK_CUR);
	      FORC4 cam_mul[(c >> 1) | ((c & 1) << 1)] = get2();
	      break;
      case 102:
	      fseek (ifp, 6, SEEK_CUR);
	      goto get2_rggb;
      case 103:
	      fseek (ifp, 16, SEEK_CUR);
	      FORC4 cam_mul[c] = get2();
      }
      if (ver97 >= 200) { // encrypted
	      if (ver97 != 205) fseek (ifp, 280, SEEK_CUR);
	      fread (buf97, 324, 1, ifp);
      }
    }

    if (tag == 0x1d) // first key (serialnumber)
      while ((c = fgetc(ifp)) && c != EOF)
        serial = serial*10 + (isdigit(c) ? c - '0' : c % 10);

    if (tag == 0xa7 && (unsigned) (ver97-200) < 12 && !cam_mul[0]) { // second key (shuttercount)
      ci = xlat[0][serial & 0xff];
      cj = xlat[1][fgetc(ifp)^fgetc(ifp)^fgetc(ifp)^fgetc(ifp)]; 
      ck = 0x60;
      for (i=0; i < 324; i++)
        buf97[i] ^= (cj += ci * ck++); // decryption
      i = "66666>666;6A"[ver97-200] - '0'; // offset depending on version : 6, 14 ('>'-'0'), 11 (';'-'0') or 17 ('A'-'0')
      FORC4 cam_mul[c ^ (c >> 1) ^ (i & 1)] =
	      sget2 (buf97 + (i & -2) + c*2);
    }
}

get2_rggb:
      FORC4 cam_mul[c ^ (c >> 1)] = get2();
      fseek (ifp, 22, SEEK_CUR);
      FORC4 sraw_mul[c ^ (c >> 1)] = get2();

}