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# @(#) $Id: MAKER_NOTES,v 1.8 2005/07/05 17:02:24 alex Exp $
Only one camera maker (Foveon, for the Sigma/Foveon camera) currently
publishes the form or interpretation of their makernote data; the data is
apparently recorded just to make the image file larger.
Exifprobe's identification and interpretation of tags in MakerNotes is
based largely upon information reverse-engineered by others and posted to
the Web (see CREDITS). A few items are based upon examination of images
downloaded from websites whose operators are kind enough to make camera
images available for download (including some rather *large* images).
I recommend that you examine any output for your camera to assure yourself
that the associations between tag identifiers and the interpretation of
the associated values is reasonable and correct. Please report to me
(dhh@virtual-cafe.com) any corrections you think should be made for any
make or model of camera, and any additional information you may deduce for
any camera (or other device).
It should be noted that tag numbers, types, and values shown by exifprobe
will be correct if shown...they are read directly from the image file. It
is the "interpretation" of tags and associated values which could be
suspect.
The strategy used by exifprobe to read MakerNotes does *not* depend upon a
table of makes and models. The program scans the offset given for the note
to see if it can find an ID string, a TIFF header, and/or a valid IFD entry
or two at a reasonable offset and in either byteorder. The features it
finds are recorded as a "scheme" which is used for reading and printing the
MakerNote information. If a valid IFD is found the program consults make
and model information for the oddball variations used by some manufacturers
(e.g. offsets relative to the start of the note or start of each entry) and
to see if tagnames and value interpretations are available. If tagnames and
interpretations are not available, the program will print the raw data with
tagnames constructed from the tag number.
dhh@virtual-cafe.com
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