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Some thoughts on IIIF and Metadata « Jakoblog — Das Weblog von Jakob Voß

Some thoughts on IIIF and Metadata

5. Mai 2017 um 22:40 1 Kommentar

Yesterday at DINI AG Kim Workshop 2017 I Martin Baumgartner and Stefanie Rühle gave an introduction to the International Image Interoperability Framework (IIIF) with focus on metadata. I already knew that IIIF is a great technology for providing access to (especially large) images but I had not have a detailed look yet. The main part of IIIF is its Image API and I hope that all major media repositories (I am looking at you, Wikimedia Commons) will implement it. In addition the IIIF community has defined a „Presentation API“, a „Search API“, and an „Authentication API“. I understand the need of such additional APIs within the IIIF community, but I doubt that solving the underlying problems with their own standards (instead of reusing existing standards) is the right way to go. Standards should better „Do One Thing and Do It Well“ (Unix philosophy). If Images are the „One Thing“ of IIIF, then Search and Authentication are different matter.

In the workshop we only looked at parts of the Presentation API to see where metadata (creator, dates, places, provenance etc. and structural metadata such as lists and hierarchies) could be integrated into IIIF. Such metadata is already expressed in many other formats such as METS/MODS and TEI so the question is not whether to use IIIF or other metadata standards but how to connect IIIF with existing metadata standards. A quick look at the Presentation API surprised me to find out that the metadata element is explicitly not intended for additional metadata but only „to be displayed to the user“. The element contains an ordered list of key-value pairs that „might be used to convey the author of the work, information about its creation, a brief physical description, or ownership information, amongst other use cases“. At the same time the standard emphasizes that „there are no semantics conveyed by this information“. Hello, McFly? Without semantics conveyed it isn’t information! In particular there is no such thing as structured data (e.g. a list of key-value pairs) without semantics.

I think the design of field metadata in IIIF is based on a common misconception about the nature of (meta)data, which I already wrote about elsewhere (Sorry, German article – some background in my PhD and found by Ballsun-Stanton).

In a short discussion at Twitter Rob Sanderson (Getty) pointed out that the data format of IIIF Presentation API to describe intellectual works (called a manifest) is expressed in JSON-LD, so it can be extended by other RDF statements. For instance the field „license“ is already defined with dcterms:rights. Addition of a field „author“ for dcterms:creator only requires to define this field in the JSON-LD @context of a manifest. After some experimenting I found a possible way to connect the „meaningless“ metadata field with JSON-LD fields:

  "@context": [
      "author": "http://purl.org/dc/terms/creator",
      "bibo": "http://purl.org/ontology/bibo/"
  "@id": "http://example.org/iiif/book1/manifest",
  "@type": ["sc:Manifest", "bibo:book"],
  "metadata": [
      "label": "Author",
      "property": "http://purl.org/dc/terms/creator",
      "value": "Allen Smithee"
      "label": "License",
      "property": "http://purl.org/dc/terms/license",      
      "value": "CC-BY 4.0" 
   "license": "http://creativecommons.org/licenses/by/4.0/",
   "author": {
     "@id": "http://www.wikidata.org/entity/Q734916",
     "label": "Allen Smithee"

This solution requires an additional element property in the IIIF specification to connect a metadata field with its meaning. IIIF applications could then enrich the display of metadata fields for instance with links or additional translations. In JSON-LD some names such as „CC-BY 4.0“ and „Allen Smithee“ need to be given twice, but this is ok because normal names (in contrast to field names such as „Author“ and „License“) don’t have semantics.

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