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88 lines
4.6 KiB
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88 lines
4.6 KiB
HTML
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<h1>MakerNote Formats and Specifications</h1>
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<p>
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The Makernote is tag 0x927c in the Exif IFD. According to the
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<a title="The Exif 2.2 standard (PDF)" href="http://www.exif.org/Exif2-2.PDF">
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Exif 2.2 standard</a>, the makernote is <i>"a tag for manufacturers of
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Exif writers to record any desired information. The contents are up to
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the manufacturer, but this tag should not be used for any other than
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its intended purpose."</i></p>
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<p>Most vendors do not publish their makernote specifications. Most of the
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<a href="#R0">specifications available on the Internet</a>
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were reverse-engineered. Judging from the size of many makernote
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fields, manufacturers store a lot of information there and from the
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available specifications, some of this is certainly quite
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interesting. For example, makernotes may contain information about the
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lens used, contrast, saturation and sharpness settings, image quality
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settings, etc. For some more advanced camera settings, the Exif
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standard doesn't define a standard tag, so camera vendors have to
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resort to using the makernote. Unfortunately, in some cases, camera
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vendors store important information only in proprietary makernote
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fields, instead of using available Exif standard tags. The most
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infamous example for this is Nikon's ISO settings tag.</p>
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<p>Most vendors write the makernote in TIFF format, i.e., in the same
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format as the rest of the Exif information is encoded. This appears to
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be a sensible thing at first glance. Unfortunately, in general it
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means that <i>any</i> change of an Exif tag, which moves the
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makernote field, will corrupt it. It is an inherent problem of the
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TIFF format that a writer must know the format and all extensions
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used, in order to be able to write changes correctly; unknown tags are
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potentially corrupted when they are moved (rearranged). But since
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makernotes are usually proprietary, Exif writers often don't know
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these details. The reason to write to the Exif data could be as simple
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as to add copyright information, an Exif comment, etc. Some camera
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manufacturers seem to have recognized this problem and now use a
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modified TIFF format with offsets relative to somewhere at the
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beginning of the makernote field for the makernote IFD to address the
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issue.</p>
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<p>The following table summarizes the structures of the makernote
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field used by some vendors. Please let me know if you have additional
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information.</p>
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__makernotes__
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<p><a href="http://www.exif.org/">Exif.org</a> has another table with similar
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info and sample pictures: <a href="http://www.exif.org/samples.html">Digital
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Camera Sample Images</a>. According to this source, (at least some) Ricoh and
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Kodak cameras do not write the makernote in IFD format.</p>
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<h2><a name="R0">References</a></h2>
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<p><a name="R1">[1]</a> <a href="http://park2.wakwak.com/%7Etsuruzoh/Computer/Digicams/exif-e.html">Exif
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file format</a> by TsuruZoh Tachibanaya<br>
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<a name="R2">[2]</a> <a href="http://www.burren.cx/david/canon.html">EXIF Makernote
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of Canon</a> by David Burren<br>
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<a name="R3">[3]</a> <a href="http://www.tawbaware.com/990exif.htm">Makernote
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EXIF Tag of the Nikon 990</a> by Max Lyons<br>
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<a name="R4">[4]</a> <a href="http://www.dicasoft.de/casiomn.htm">"Makernote"
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Exif tag of Casio</a> by Eckhard Henkel<br>
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<a name="R5">[5]</a> <a href="http://www.dalibor.cz/minolta/makernote.htm">Minolta
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MakerNote</a> by Dalibor Jelinek<br>
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<a name="R6">[6]</a> <a href="http://www.exif.org/makernotes/SanyoMakerNote.html">Sanyo
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MakerNote</a> by John Hawkins<br>
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<a name="R7">[7]</a> <a href="http://www.x3f.info/technotes/FileDocs/MakerNoteDoc.html">
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SIGMA and FOVEON EXIF MakerNote Documentation</a> by Foveon<br>
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<a name="R8">[8]</a> <a href="http://www.compton.nu/panasonic.html">Panasonic
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MakerNote Information</a> by Tom Hughes<br>
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<a name="R9">[9]</a> <a href="http://www.ozhiker.com/electronics/pjmt/jpeg_info/makernotes.html">
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Various Makernote specifications</a> from the <a href="http://www.ozhiker.com/electronics/pjmt/index.html">
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PHP JPEG Metadata Toolkit</a> by Evan Hunter<br>
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<a name="R10">[10]</a> <a href="http://www.sno.phy.queensu.ca/~phil/exiftool/">ExifTool</a>, the most complete and up-to-date tool for reading and writing meta information in image files, by Phil Harvey<br>
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<a name="R11">[11]</a> <a href="http://www.gvsoft.homedns.org/exif/makernote-pentax-type3.html">EXIF: Pentax type3 Makernotes</a> by Ger Vermeulen</p>
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<a name="R12">[12]</a> <a href="http://www.gvsoft.homedns.org/exif/makernote-casio-type1.html">Casio MakerNote Information</a>
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