Daejeon, July 27–31
artresearch.net is the open research platform of the PHAROS consortium, designed to enable multimodal, cross-archive searches of art-historical photographs.
https://artresearch.net/, last accessed 26 April 2026. One example is the
Arbeitsgemeinschaft kunsthistorischer Bildarchive und Fototheken (AKBF), founded in 2004, which is an association of image archives from German research and cultural institutions. In November 2025, the platform attracted 12,065 unique visitors, 13,380 total visits, and 50,269 page views.
PHAROS is an international consortium of 12 art-historical photo archives based in North America and Europe.
For the list of partner institutions, see
https://artresearch.net/resource/Partners (last accessed 26 April 2026). https://www.frick.org/library, last accessed 26 April 2026.
artresearch.net provides unified access to the photographic collections and scholarly documentation held by PHAROS member institutions. The following sections outline the scope of the aggregated data and the technical infrastructure that underpins the platform, with particular attention to its multimodal search capacities.
| (a) | (b) |
Figure 1. Frontend of artresearch.net. (a) The search view presents the results, accompanied by a faceted search panel. (b) The record view displays the image and its associated metadata, with each field attributed to the providing institution.
Although the individual member institutions differ in their collection profiles, documentation practices, and research priorities, the knowledge contained within their databases is fundamentally complementary: each archive engages, in its own way, with the same core entities—artworks, their photographic reproductions, and the scholarly contexts that surround them. To render this shared knowledge interoperable, data are ingested from a wide range of source formats, transformed into a shared data model, and—where necessary—reconciled against external authority vocabularies such as the
Art & Architecture Thesaurus (AAT).
For a discussion of common usability challenges in entity reconciliation workflows, see Daquino / Kozlov / Mambelli (2026).
| Institution | Photographs | Artworks |
| Bibliotheca Hertziana | 348,251 | 273,704 |
| Bildarchiv Foto Marburg | 769,375 | 402,763 |
| Fondazione Federico Zeri | 153,098 | 85,616 |
| Frick Art Research Library | 366,370 | 259,923 |
| Kunsthistorisches Institut in Florenz | 94,629 | 131,219 |
| RKD (Netherlands Institute for Art History) | 423,200 | 301,628 |
| Warburg Institute | 105,208 | 105,208 |
Table 1. Descriptive statistics of the data provided in artresearch.net by PHAROS member institutions.
artresearch.net is built on ResearchSpace, an open-source semantic research environment originally developed by the British Museum. It leverages
Linked Open Data (LOD) technologies to move toward more dynamic and context-rich modes of information discovery (Oldman / Tanase / Santschi 2019). Within artresearch.net, data are published in accordance with the CIDOC
Conceptual Reference Model (CRM) ontology. Collections are transformed into RDF and made queryable through SPARQL endpoints, with RDF stored in a Blazegraph triplestore; an IIIF-compliant image server ensures the delivery of high-resolution images.
For further technical details, see Klic (2022). https://github.com/artresearch, last accessed 26 April 2026.
artresearch.net supports a wide range of scholarly practices—from locating specific artworks to uncovering previously unrecognized visual relationships across heterogeneous collections. To accommodate this diversity, the platform combines text-based and image-based search.
Text Match identifies records in which query terms appear verbatim within metadata fields such as titles or artist names.
Textual Similarity enables concept-driven and multilingual exploration by embedding textual metadata in a shared vector space. Extending this approach across modalities,
Visual Similarity translates textual queries into visual embeddings, allowing users to retrieve artworks corresponding to described compositional, stylistic, or aesthetic features. Image-based search likewise distinguishes between exact and similarity-based modes.
Visual Match detects near-identical reproductions by comparing digital fingerprints of images, supporting tasks such as cross-archive reconciliation.
Visual Similarity retrieves artworks related to a given image in terms of style, palette, composition, or subject matter, enabling the identification of broader visual affinities rather than direct copies. Textual metadata are embedded using the Qwen3 model with 8 billion parameters (Yang et al. 2025). Cross-modal and image-based search rely on the NaFlex variant of the SigLIP 2 model with 400 million parameters (Tschannen et al. 2025). For near-exact image retrieval, similarity rankings are refined using RootSIFT feature matching (Arandjelovic / Zisserman 2012) with geometric verification via MAGSAC (Barath / Matas / Noskova 2019). To support interpretability, search results are labeled with indicators denoting the retrieval strategies employed (i.e.,
Text Match,
Textual Similarity,
Visual Match, or
Visual Similarity), with records satisfying multiple criteria being prioritized in the ranking (Figure 1a).
See also
https://artresearch.net/resource/search-help (last accessed 26 April 2026).
Beyond retrieval, artresearch.net treats representation as a first-class research problem. Because the holdings of current PHAROS members are largely oriented towards European and North American cultural heritage, expanding this geographical and cultural scope—especially through engagement with photo archives focusing on non-Western art—is a central objective of the consortium. In parallel, artresearch.net intends to make structural biases analytically tractable by documenting collection histories, exposing asymmetries in representation, and developing tools that allow scholars to examine patterns of exclusion across collections. Concretely, this includes revealing coverage through facets (e.g., geography or period) and making unknown descriptive patterns visible for interpretation rather than treating them as noise. By doing so, artresearch.net contributes an infrastructure for multimodal, cross-archive research at a scale and granularity that is difficult to achieve through institutional portals.
artresearch.net was funded by the Samuel H. Kress Foundation, the Andrew W. Mellon Foundation, the Bibliotheca Hertziana, and the National Endowment for the Humanities.