Zurich's Digital Archives Are Full of the Same Photo Twice — Officials and Experts Are Pushing Back

Zurich's public institutions are sitting on millions of duplicate digital images, and the people responsible for managing them say the problem has quietly grown into a serious administrative and financial headache. Stadtarchiv Zürich, ETH Zürich's image library, and the Zentralbibliothek on Zähringerplatz are among the bodies now openly acknowledging that redundant image files are consuming storage budgets, slowing database searches, and undermining the credibility of publicly accessible collections.

The timing is not accidental. A national digital preservation initiative launched under the Federal Office of Culture in Bern set a 2026 compliance deadline for major cantonal institutions to audit and rationalise their digital holdings. For Zurich, that deadline is forcing conversations that have been deferred for years.

Why the Problem Kept Growing

The root causes are straightforward. When institutions digitised physical collections in waves — Zürich's main digitisation push ran across roughly 2010 to 2020 — the same photograph or document was often scanned by separate departments with no cross-referencing system in place. A single aerial photograph of the Limmatquai taken in 1962 might exist in three formats, stored under different file names, across two separate servers. Multiply that by hundreds of thousands of items and the waste accumulates fast.

Storage is not free. Industry pricing for institutional cold-storage archiving in Switzerland currently runs at several hundred francs per terabyte annually once security, redundancy and access costs are factored in. ETH Zürich's library directorate has publicly noted that its digital infrastructure costs have risen significantly over the past five years, though specific budget figures have not been published in verifiable public documents. The Zentralbibliothek, which holds one of the largest photographic collections in the German-speaking world, runs a publicly accessible digitisation portal — e-rara and its linked image tools — where duplicate entries are visible to any researcher who searches systematically.

Experts in digital asset management argue that the Zurich situation is common across European cities but that Swiss institutions face a particular version of the problem: multiple language regions, cantonal sovereignty, and a tradition of institutional independence that makes cross-body deduplication politically awkward even when technically straightforward. Algorithms capable of identifying near-duplicate images — comparing pixel hashes or metadata timestamps — exist and are in commercial use. The obstacle is not the technology.

What Officials and Sector Figures Are Saying

No named official has yet made a public statement directly on Zurich's duplicate image backlog, but the policy direction is legible in recent procurement notices and committee minutes published by Stadt Zürich's Informatik department. A tender issued in spring 2026 for digital asset management software listed deduplication capability as a required function — a specification that was absent from the equivalent 2021 tender. That shift in language signals where institutional priorities have moved.

At ETH Zürich on Rämistrasse, researchers in the Digital Humanities lab have been developing metadata standards that would, in principle, allow image collections held by different Zurich institutions to cross-reference one another. The project, part of the Swiss National Science Foundation's broader data infrastructure programme, is scheduled to publish its first interoperability framework by the end of 2026. Whether individual institutions adopt it will depend on resources and political will at the cantonal level.

The Zentralbibliothek has separately announced a review of its digital catalogue scheduled for the third quarter of 2026. Staff there have told users via their public newsletter that the review will address duplicate records, though the scope and methodology have not been specified in documents available to this newspaper.

For researchers, archivists and the curious Zürich resident using these collections, the practical advice is straightforward: search across multiple portals — e-rara, the Stadtarchiv's online finder, and ETH's e-pics image archive — when looking for historical images, because the same file may appear under different accession numbers with different quality scans. The better copy is not always the one that surfaces first. Until the deduplication work is complete, manual cross-checking remains the most reliable method. That is, by any measure, an inefficient way to run a world-class archive in 2026.