Awesome

Exif to RDF

This tiny tool extracts Exif data from a JPEG image file, and converts it into RDF/XML. Provide image file path as an argument, then it outputs the resulting RDF to STDOUT.

perl exif2rdf.pl <imagefile>

Requires definition file "exif-tags.json" in the same directory. Also requires Image::ExifTool and JSON modules.

Tag-RDF Definition JSON

exif-tags.json is a mapping file from Exif tag number to RDF property (defined in Exif data description vocabulary ).

The root object has keys as Eixf tags, and each value object has RDF property name propName and additional information such as default, or values array to map Exif values to RDF objects .

{
	"283" : {
		"propName" : "yResolution",
		"default" : "72",
		"datatype" : "&xsd;decimal"
	},
	"284" : {
		"propName" : "planarConfiguration",
		"values" : {
			"1" : "chunky-format",
			"2" : "planar-format"
		}
	}
}

The above example describes that

• tag 283 will be interpreted as RDF property yResolution whose datatype is xsd:decimal, and default value is 72.
• tag 284 as property planarConfiguration, and for Exif value 1 the RDF value is chunky-format, and Exif 2 the RDF planar-format.

Note that tag numbers for GPS IFD, Interoperability IFD and PIM IFD will have a prefix 'g', 'i' and 'p' respectively.

Background

This is an old perl script written in 2007, but still works (as of 2017). See also a half-written document about Photo and RDF (mostly in Japanese).