Zurich's Digital Archives Face a Hidden Crisis: What Officials, Experts and Key Figures Are Saying About Duplicate Image Replacement

Thousands of digital images catalogued twice, stored three times, and occasionally labelled under conflicting identifiers — Zurich's public institutions are sitting on a duplicate image problem that archivists say is larger, and more expensive, than most administrators want to admit. The issue has gained traction this summer after a working group at ETH Zurich flagged the scale of redundancy in several publicly funded digital repositories, prompting calls for a coordinated replacement and deduplication strategy across the city's cultural and civic infrastructure.

The stakes are real. Digital storage is not free. Institutions running redundant image libraries pay for server capacity, backup cycles, and metadata management on files they already hold under a different filename or catalogue number. For organisations under budget pressure — and Zurich's cultural institutions have faced tighter cantonal allocations since 2024 — that overhead adds up fast.

What the Specialists Are Saying

Archivists and digital preservation officers at two of Zurich's largest public collections have been pointing to the same structural failure: images digitised in separate project phases, without cross-referencing against existing holdings, end up duplicated in perpetuity. The Stadtarchiv Zürich, housed on Neumarkt in the Altstadt, and the Zentralbibliothek Zürich on Zähringerplatz both run substantial image collections covering historical photography, planning documents, and printed ephemera. Neither institution confirmed specific duplication figures to The Daily Zurich, but both are known to be participants in discussions about shared metadata standards under the Swiss cultural heritage framework Memoriav.

Experts in digital asset management outside the public sector have been more direct. Specialists working with Zurich-based pharmaceutical and financial firms — sectors that manage enormous proprietary image databases, from clinical trial photography to architectural renders for new campuses — describe duplicate replacement as a solved problem in corporate environments, but one that public archives have been slow to adopt. The disconnect, they say, lies in procurement cycles and the absence of a central mandate.

At ETH Zurich, whose library system on Rämistrasse holds one of the largest scientific image archives in the German-speaking world, the working group's recommendations reportedly include adopting perceptual hashing — a technique that identifies visually identical or near-identical images regardless of filename or format — as a standard pre-ingestion step. The approach is already used by major news agencies and stock image platforms. Applying it systematically before any new batch of images enters a public repository would prevent new duplicates from accumulating, even if clearing existing backlogs remains a longer project.

The Practical and Political Dimension

The conversation is not purely technical. Zurich's direct democracy tradition means that significant IT procurement decisions touching public institutions can become subjects of cantonal debate, particularly when costs are visible on a budget line. A coordinated deduplication project across the Stadtarchiv, Zentralbibliothek, and the Kunsthaus Zürich on Heimplatz — all of which digitised large holdings at different points over the past fifteen years — would require both political backing and interoperability agreements between institutions that operate under different cantonal and municipal mandates.

There is also the question of what happens to the replaced duplicate. Archivists are careful to distinguish between true duplicates — byte-for-byte identical files — and near-duplicates, where different scans of the same physical object may each carry unique metadata, condition information, or resolution characteristics. Deleting the wrong copy can mean losing provenance data that took years to assemble. The replacement workflow, specialists emphasise, must be more than a bulk delete operation.

A practical next step being discussed among institutions is a pilot project confined to a single collection category — historical street photography of Zürich-West, for instance, where multiple digitisation drives have produced clear overlaps — before any city-wide approach is formalised. If the cantonal cultural affairs office backs the pilot with even modest funding before the end of the 2026 budget year, participants say it could serve as a template exportable to other Swiss cities grappling with the same problem. The window to act before another digitisation cycle begins is, by most accounts, relatively short.