Get tiff field tag value from field information
#include <tiffio.h>
uint32 TIFFFieldTag(const TIFFField* fip)
TIFFFieldTag returns the numeric tag value for a TIFF field. This can be compared to various constants exported by the libtiff header files, such as TIFFTAG_IMAGEWIDTH.
fip is a field information pointer previously returned by TIFFFindField, TIFFFieldWithTag, or TIFFFieldWithName.
TIFFFieldTag returns an integer tag value.
libtiff(3TIFF),
Libtiff library home page: http://www.remotesensing.org/libtiff/