Newbie Question about Duplicate data or reading from same field: XMP vs EXIF and IPTC
If I use Jeffrey's EXIF reader http://exif.regex.info/exif.cgi
for this image https://www.controlledvocabulary.com/images/drp2091169-sfw-q60-all-wicc.jpg
I find a lot of duplicate data in the XMP results that are in the IPTC or EXIF results.
Is each set of data written twice (and thus I presume could be written as different data) or is the XMP section reading the data from the single EXIF pr IPTC field?
I am aware that a lot of XMP data is unique - (maybe it is all unique)
IPTC Urgency 1 (most urgent)
XMP Urgency 1 (most urgent)
IPTC Source David Riecks Photography
XMP Source David Riecks Photography
XMP Location Created Province State District of Columbia
XMP Location Shown Province State District of Columbia
IPTC Province-State District of Columbia
XMP State District of Columbia
IPTC Object Name drp2091169d
XMP Title drp2091169d
IPTC Headline Lincoln Memorial
XMP Headline Lincoln Memorial
XMP Location Shown Sublocation Lincoln Memorial
IPTC Sub-location Lincoln Memorial
XMP Instructions Newsmagazines Out
IPTC Special Instructions Newsmagazines Out
XMP Country United States of America
IPTC Country-Primary Location Name United States of America
IPTC Country-Primary Location Code US
XMP Location Created Country Code US
IPTC City Washington
XMP City Washington
RE: Newbie Question about Duplicate data or reading from same field: XMP vs EXIF and IPTC - Added by Colin K 15 days ago
To answer my own question, it appears that while it is possible to write data to IPTC and XMP the IPTC standard is now included within XMP eg
XMP:XMP-iptcExt LocationShownCity Washington
So a new question, is there any benefit / are there any circumstances where I might want to write data to both IPTC and XMP eg adding a Headline, Keywords or Caption-Abstract in both IPTC and XMP but use slightly different words - maybe for SEO purposes?
RE: Newbie Question about Duplicate data or reading from same field: XMP vs EXIF and IPTC - Added by Phil Harvey 15 days ago
The old IPTC standard used what is known as IIM format, but they have since moved to XMP format which should be used now. But IPTC/IIM must still be used in support of older software or old files. The MWG (http://www.metadataworkinggroup.org/) gives recommendations for how to reconcile tags in EXIF, IPTC/IIM and XMP, but doesn't specifically address all of the tags you mention.
Personally, now I would recommend writing only XMP and converting any old IPTC/IIM to XMP if possible, although support for XMP in current software is still not universal. I would be surprised if there was an advantage to also write IPTC/IIM for SEO purposes.