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# MakerNote Formats and Specifications

The Makernote is tag 0x927c in the Exif IFD. According to the Exif 2.2 standard, the makernote is "a tag for manufacturers of Exif writers to record any desired information. The contents are up to the manufacturer, but this tag should not be used for any other than its intended purpose."

Unfortunately, most vendors do not publish their makernote specifications. (Why not?) Most of the specifications available on the Internet were reverse-engineered. Judging from the size of many makernote fields, manufacturers apparently store a lot of information there and from the available specifications, some of this is certainly quite interesting. For example, makernotes may contain information about the lens used, contrast, saturation and sharpness settings, image quality settings, etc.

Many (but not all) vendors write the makernote in TIFF IFD (Image File Directory) format, i.e., in the same format as the rest of the Exif information is encoded. Although this may appear to make sense at first glance, it actually complicates the situation for programs that attempt to write to the Exif data. The problem is that IFDs contain offsets relative to the start of the Exif data. That implies that if an Exif writer moves a makernote field encoded in IFD format to a different location within the Exif data, it gets corrupted. The reason to write to the Exif data could be as simple as to add copyright information, an Exif comment, etc. In my opinion, this is a bug in the specification. In fact, some vendors seem to have recognized this problem and use offsets relative to somewhere at the beginning of the makernote field for the makernote IFD.

The following table summarizes the structures of the makernote field used by some vendors. Please let me know if you find further specifications on the Internet.

Make | Format | Header | Endian 1) | Offsets 2) | Ref | Remarks
--- | --- | --- | --- | --- | --- | ---
Canon | IFD | None |  |  | [2] | Some CR2 images have a non-zero next-IFD pointer
Casio | IFD | - | - | - | [4] | Not supported by Exiv2 yet
FUJIFILM | IFD, usually at offset 12 | Starts with the string "FUJIFILM" and a 4 byte pointer to the IFD | Little-endian (II) | Relative to the beginning of the makernote | [1] | Exif data uses big-endian (MM) byte order
Minolta, KONICA MINOLTA | IFD | None |  |  | [5] | Camera settings tag is encoded in big-endian (MM) style, regardless of the encoding style of the Exif data
NIKON | IFD | None |  |  | [3] | Models using this makernote include E990, D1
NIKON | IFD, at offset 8 | "Nikon\0" followed by two bytes of unknown meaning |  |  | [1] | Models using this makernote include E700, E800, E900, E900S, E910, E950
NIKON | IFD, usually at offset 18 | "Nikon\0" followed by 4 bytes which look like a version code and a TIFF header | From makernote TIFF header | Relative to the start of the makernote TIFF header |  | Models using this makernote include E5400, SQ, D2H, D70, D100, D200. Makernote IFD of the D200 has no next-IFD pointer. (Is this a bug?)
OLYMPUS | IFD, at offset 8 | "OLYMP\0" followed by two bytes of unknown meaning |  |  | [1] |
Sanyo | IFD | - | - | - | [6] | Not supported by Exiv2 yet
SIGMA, FOVEON | IFD, at offset 10 | "SIGMA\0\0\0" or "FOVEON\0\0" followed by two bytes of unknown meaning |  |  | [7] |
Panasonic | IFD without a next-IFD pointer at offset 12 | "Panasonic\0\0\0" |  |  | [8] |
SONY | IFD without a next-IFD pointer at offset 12 | "SONY DSC \0\0\0" |  |  |  | Seen in Jpeg images, e.g., from DSC-W7, DSC-R1
SONY | IFD | None |  |  |  | Seen in SR2 images, e.g., from DSC-R1

1) If not specified, the byte order of the Exif data is applicable.
2) If not specified, offsets are relative to the start of the TIFF header.

Exif.org has another table with similar info and sample pictures: Digital Camera Sample Images. According to this source, (at least some) Ricoh and Kodak cameras do not write the makernote in IFD format.

## References

[1] Exif file format by TsuruZoh Tachibanaya
[2] EXIF Makernote of Canon by David Burren
[3] Makernote EXIF Tag of the Nikon 990 by Max Lyons
[4] "Makernote" Exif tag of Casio by Eckhard Henkel
[5] Minolta MakerNote by Dalibor Jelinek
[6] Sanyo MakerNote by John Hawkins
[7] SIGMA and FOVEON EXIF MakerNote Documentation by Foveon
[8] Panasonic MakerNote Information by Tom Hughes
[9] Various Makernote specifications from the PHP JPEG Metadata Toolkit by Evan Hunter
[10] ExifTool, the most complete and up-to-date tool for reading and writing meta information in image files, by Phil Harvey