Some properties (such as Licensor which is used for Google’s Licensable feature) are structured, which means they contain sub-properties. In this case, running the simple exiftool -XMP-plus:Licensor test-image.jpg returns no results.
View all properties read by Google Image Search for Licensable badge and Synthetic Media features
% exiftool -G1 -XMP-dc:creator -XMP-photoshop:Credit -XMP-dc:rights -XMP-xmpRights:WebStatement -XMP-plus:LicensorURL -XMP-iptcExt:DigitalSourceType test-image.jpg
[XMP-dc] Creator : New Creator, Additional Creator, Additional Creator
[XMP-photoshop] Credit : New Credit Line
[XMP-dc] Rights : New Rights line
[XMP-xmpRights] Web Statement : New Web Statement of Rights
[XMP-plus] Licensor URL : http://www.newlicensorurl.com/
[XMP-iptcExt] Digital Source Type : https://cv.iptc.org/newscodes/digitalsourcetype/trainedAlgorithmicMedia
View the full XMP data for an image file
This displays the internal structure of the XMP packet that is stored within an image file. This is usually only needed for debugging purposes or if you are curious about how XMP metadata is actually stored inside the file.
$ exiftool -b -xmp IPTC-PhotometadataRef-Std2021.1.jpg
<?xpacket begin='' id='W5M0MpCehiHzreSzNTczkc9d'?>
<x:xmpmeta xmlns:x='adobe:ns:meta/' x:xmptk='Image::ExifTool 12.34'>
<rdf:li xml:lang='x-default'>This is the Alt Text description to support accessibility in 2021.1</rdf:li>
[... much more data snipped for brevity ...]
Examples of writing IPTC metadata on the command line using ExifTool
The same ExifTool XMP tags can be used to write metadata to image files on the command line.
Note that by default when writing to an image file using exiftool on the command line, the original unaltered version of the image is backed up as <filename>_original, for example test-image.jpg_original. This can be a life saver!
Note that this approach will not work if there are already two or more Licensor records in the image metadata. This is because the exiftool argument -XMP-plus:LicensorURL is a shortcut for “the LicensorURL sub-property in the first Licensor structure in the image.” But for most images, there will be only one licensor record or more likely no records at all, so this shortcut will work.
If you need to edit the LicensorURL of an image with two or more Licensor records, you should use the
Writing Web Statement of Rights metadata
This triggers the “Licensable” badge in Google image search results.