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January 2007

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2007.01.12 01:29 "DNG, MakerNotes, and libtiff", by Matt Longnecker

hi folks,

My company has decided to adopt the DNG format for archiving certain
images and their associated meta-data.  We'd like to be able to
leverage libtiff for reading and writing our image files.

Specifically, I want to
-store a "raw" image in the first IFD
-store the DNG meta-data in the first IFD
-store the Exif meta-data in an ExifIFD
-store my custom meta-data in a MakerNotes block

I'd been pondering structuring my MakerNotes block as a "private IFD".
 However, there's a problem with that: the DNG spec insists that
MakerNote data must not be byte-order dependent. An IFD in isolation
is not byte-order independent.  Consequently, I'm now considering
structuring my MakerNote block as a full embedded TIFF file (with its
own image file header, byte order, and magic number.)

What level of support does libtiff have for reading and writing the
ExifIFD?  Is it still nascent?  Does bug 1320 address that issue?
What about the contrib/pds directory?

Hints and tips are appreciated.  I hope to be able to return the favor
once I'm more familiar with the library.

thanks,
Matt Longnecker (via gmail)