NFDI4Culture Metadata API

In February 2025, the Data Competence Centre HERMES held an event at which Hans Brandhorst and Etienne Posthumus gave a talk on various ways to explore Iconclass, a comprehensive system for cultural content classification. Iconclass is used by numerous universities, museums and libraries worldwide to provide subject access to digital collections. Following the successful and well-attended session, the two speakers and one of the organisers, Alexandra Büttner, decided to offer a hands-on workshop on the usage and technical features of Iconclass. Together with our colleagues from the NFDI4Culture consortium, Katharina Bergmann and Andrea Polywka from the Cultural Research Data Academy as well as, Angela Kailus from the Metadata Standards Task Area a workshop was planned. Two days of interesting presentations, use cases, hands-on sessions and discussions brought together international researchers and interested parties from various disciplines. It was well attended, with 49 participants on the first day, and 36 on the second.

On the first day, the focus was on content classification and a general introduction to Iconclass. It started with an initial overview, “Iconclass, An Analogue System in a Digital World” presented by Hans Brandhorst, the editor of Iconclass. Then, Angela Kailus (NFDI4Culture, Marburg University) explained the significance of controlled vocabularies for FAIRer data. These presentations were followed by a hands-on session in smaller groups, which gave the participants the opportunity to try the classification system on some artworks themselves. Following these fruitful sessions the presentation of two projects using Iconclass rounded up the day. Marika Klebusek (Leiden University) presented the project “Alba amicorum”, an international index of early friendship or autograph books or their fragments in public and private collections . After that, Veronika Skladká (Czech Academy, Prague) presented „e-illustrace“, a database on early modern Czech book illustrations. Both of these use cases showed how to use Iconclass, how it supports research and in which different usage scenarios it can be applied.

On the second day, we delved deeper into Iconclass itself, examining some of its technical features, and took a look into the back- end system. First, Hans Brandhorst provided an overview of the technical features of the Iconclass software. Then, Karin von Wartburg and Claudio Felber from Vitrocentre Romont the Swiss Research Centre for Stained Glass and Glass Art in Romont, presented the concept of Vitrosearch and the technicalities of the database. They presented the benefits of the multilingual features of Iconclass and how it enables connections to sister portals, such as e.g., the German Corpus Vitrearum. Next, Drew Thomas, a researcher from University College Dublin, was introduced as a surprise guest. He is currently working on the use of artificial intelligence and machine learning to investigate visual communication during the Protestant Reformation. In his presentation he showed approaches of how to use ChatGPT to generate good-quality Iconclass notations necessary to classify early modern illustrations visualising faith in biblical scenes. In between, Etienne Posthumus (Iconclass developer & NFDI4Culture, FIZ Karlsruhe) led a hands-on session with the title „Enabling Discovery: A Backend Tour", encouraging participants to do some live coding. More use cases completed the second workshop day. Jan von Bonsdorff and Tobias Plebuch (both from Uppsala University) provided insights into one of their projects. In their talk, "Charting Visual and Musical Moods and Metaphors: Facilitating Cross-Modal Connections for Machine Learning and Multimodal AI,” they offered a musicologist's perspective on film scores and the function of metaphors. This finishing talk clearly illustrated that the classification system Iconclass is not only useful to art historians and researchers working with visual media, but can and should also be used in other cultural disciplines.

Overall, the participants experienced a well-balanced programme with a variety of topics that brought together different challenges, experiences, and insights regarding the use and adaptation of Iconclass.

Individual slides can be viewed here: https://cloud.nfdi4culture.de/s/yR7pKm4WoLyor3H