Exiv2 library supports:
* full read and write access to the exif and iptc metadata of an image
through exiv2 keys and standard c++ iterators
* a smart iptc implementation that does not affect data that programs like
photoshop store in the same image segment
* exif makernote support:
o makernote tags can be accessed just like any other exif metadata
o a sophisticated write algorithm avoids corrupting the makernote:
* extract and delete methods for exif thumbnails (both, jpeg and tiff
thumbnails)
* set methods for exif thumbnails (jpeg only, tiff thumbnails can be set from
individual tags)
* complete api documentation (by doxygen)
* generic lower-level classes to access ifd (image file directory) data
structures