Zurich's Digital Archives Are Full of the Same Image Twice — and Officials Want It Fixed

Zurich's public institutions are sitting on vast libraries of redundant visual data. Duplicate images — photographs filed twice, scanned documents stored under multiple names, stock visuals duplicated across departmental servers — have become a recognised drain on storage budgets and archival integrity, and specialists are now calling for coordinated action across the city's agencies and research bodies.

The issue has sharpened over the past 18 months as ETH Zurich, the Zentralbibliothek Zürich on Zähringerplatz, and several city administration departments have each quietly audited their digital holdings. What they found, according to published institutional reports, is that redundant image files routinely account for between 15 and 30 percent of total storage use in large visual collections — a figure consistent with studies from comparable European archival bodies in Berlin and Vienna.

Why the Timing Matters

The pressure is partly financial. Swiss federal data infrastructure spending is under review for the 2027 budget cycle, and Zurich's Stadtrat has signalled it wants measurable efficiency gains from city IT departments before new storage contracts are signed. At the same time, the UBS-Credit Suisse merger integration — still working through legacy document management systems — has put the question of duplicate digital assets squarely in front of compliance officers at Zurich's Paradeplatz banking corridor, where records retention rules under FINMA require precise, non-redundant document trails.

ETH Zurich's IT Services division, based on the Hönggerberg campus, has been developing automated deduplication pipelines for research image databases since early 2025. The university has not published final results, but its open-access preprint server carried a working paper in March 2026 describing hash-based matching tools capable of identifying near-duplicate scientific images — a category that includes slightly cropped or recoloured versions of the same photograph — with accuracy rates the authors described as exceeding 94 percent on test datasets of 200,000 images.

Practitioners in the field stress that the problem is not simply technical. At the Zentralbibliothek, digitisation projects covering historical Zurich photography — including material from the Baugeschichtliches Archiv, the city's architectural image collection housed near Lindenhügel — have repeatedly encountered files ingested from multiple donor sources that depict the same subject. Manual review of such overlaps is time-consuming and expensive, and without standardised metadata tagging at the point of ingestion, automated tools can miss contextually distinct images that share visual signatures.

What Experts Are Recommending

The broad thrust of expert opinion, as reflected in published conference proceedings from the 2025 DigitalHeritage Zürich symposium held at the Museum für Gestaltung on Ausstellungsstrasse, points toward three priorities. First, institutions should adopt shared metadata standards before digitising new collections, rather than attempting to deduplicate after the fact. Second, procurement of any new content management system should require built-in duplicate detection as a baseline specification. Third, cross-institutional data-sharing agreements — currently fragmented across city, cantonal and federal layers — need updating to allow libraries, archives and university repositories to flag and resolve overlaps collaboratively.

The pharmaceutical sector, centred on the Zurich-Basel corridor with major research campuses in the city's northwest, faces related pressures. Clinical trial image data — microscopy, radiology, histology — is subject to strict retention and uniqueness requirements under Swissmedic regulations. Industry compliance specialists have noted publicly that deduplication errors in this context carry regulatory risk, not just storage inefficiency.

The Stadtrat's technology committee is expected to receive a consolidated report on digital asset management practices across city departments by September 2026. That report will inform whether Zurich moves toward a unified deduplication framework or leaves individual institutions to manage the problem independently. Archivists at the Zentralbibliothek and technology officers at ETH have both indicated, in published statements and conference remarks, that a coordinated city-level standard would significantly reduce costs and improve the long-term reliability of Zurich's public digital record. Without one, the same image will keep getting filed twice — and someone will keep paying for the extra copy.