How PHOTARCH aligns with — and differs from — existing imaging and metadata standards.
The need for standardisation in cultural heritage imaging has long been recognised. Institutions such as the Library of Congress and the National Library of the Netherlands have published detailed technical guidelines to ensure the preservation quality, colour fidelity, and long-term accessibility of digital surrogates (FADGI, 2023; Metamorfoze, 2012). PHOTARCH builds upon the foundation laid by these initiatives, while adapting their principles to the specific demands of archaeological artefact photography. Unlike flat document scanning or general digitisation workflows, photographing three-dimensional, textured, and context-rich objects in archaeology requires additional considerations: angle control, physical scale, lighting structure, and a consistent visual logic across entire collections.
The FADGI guidelines (Federal Agencies Digital Guidelines Initiative) outline a multi-star rating system that specifies measurable targets for resolution, noise, colour accuracy, and tonal response. Although these metrics were originally developed for scanning and reprographic capture, many of their technical expectations — such as use of ICC profiles, inclusion of colour targets, and control over tonal range — are directly applicable to photographic documentation (FADGI, 2023). Metamorfoze, similarly, sets minimum image quality standards for digitisation projects in libraries and archives, with emphasis on lossless formats, proper lighting, and colour management workflows (Metamorfoze, 2012). Both standards provide invaluable baselines for understanding image quality, but neither was built specifically for artefacts or archaeological contexts.
Archaeological artefacts are materially complex, often irregular, and typically require multi-angle documentation. They are also tightly linked to context — spatial, typological, and comparative — which places higher demands on metadata and repeatability. A single image of a ceramic sherd is not simply a visual object; it is part of a broader system of interpretation involving typology, chronology, and provenance. PHOTARCH addresses these needs by extending existing image standards into a domain-specific method. It integrates lighting geometry and physical reference tools to allow direct comparison between objects from different collections, countries, and excavations. This supplements — rather than replaces — standards like FADGI and Metamorfoze.
Every object record in PHOTARCH is mapped to established descriptive standards.
Dublin Core provides the base layer of interoperability. The fifteen core elements — title, type, date, creator, rights, and so on — are populated for every object and available for export as XML. This makes records readable by any system that understands Dublin Core, including institutional repositories and library catalogues.
LIDO (Lightweight Information Describing Objects) is the standard used by European museum networks and aggregators. PHOTARCH generates a LIDO v1.0 XML file per object, covering object classification, repository information, production event, material, technique, dating, find spot, and rights. This export is intended for submission to national heritage portals and cross-collection discovery platforms.
EXIF and IPTC metadata are embedded directly in image files at ingest. Camera-generated EXIF data (capture date, focal length, exposure settings) is preserved alongside descriptive IPTC fields (title, caption, rights, photographer). This ensures that every image file carries its own documentation regardless of where it ends up.
Every object in PHOTARCH carries an ARK persistent identifier (Archival Resource Key) under NAAN 73195. ARKs are resolvable, stable identifiers that remain valid even if the URL structure of the archive changes. The identifier appears on each object record and resolves via the PHOTARCH resolver at app.photarch.com/id/.
ARKs were developed by the California Digital Library and are used by major institutions including the Bibliothèque nationale de France and the Internet Archive. They carry no licensing fees and require no institutional membership.
All images stored in PHOTARCH are assigned a SHA-256 checksum at the time of upload. The checksum is displayed on each object record and included in bulk CSV exports. This allows institutions and researchers to verify that a file has not been altered since it was ingested — a basic requirement for archival trust.
PHOTARCH supports the following export formats for all object records:
One of PHOTARCH’s key ambitions is to make archaeological photography machine-readable without sacrificing human interpretability. By structuring camera angles, embedding metadata, and ensuring visual consistency, the method supports not only comparison and education, but also AI-driven categorisation and automated analysis. As cultural heritage data becomes increasingly digitised, the role of visual standards grows in both technical and ethical importance. A standardised photographic approach ensures not only preservation and accessibility — but also the ability to see, study, and share artefacts more clearly across generations.