Zurich's War on Duplicate Images: What Officials, Experts and Key Figures Are Saying

Zurich's public sector is sitting on a growing problem it rarely talks about publicly: thousands of duplicate digital images clogging the archives of municipal agencies, research institutions and urban planning databases, costing both storage budget and staff hours. The issue came into sharper focus this spring when the Stadtarchiv Zürich, located on Neumarkt in the Altstadt, flagged in its 2025 annual review that near-identical photographic records were hampering search efficiency across shared city repositories.

The timing matters. Zurich's housing shortage — Wohnungsnot — has forced the Amt für Städtebau to accelerate its digital documentation of building permits, neighbourhood surveys and heritage assessments across districts from Schwamendingen to Wiedikon. Faster digitisation means more images, and without automated deduplication tools, archive staff are manually reviewing files that may have been scanned two or three times under different metadata tags. That is not a sustainable workflow for a city running lean budgets in the post-Credit Suisse financial environment.

What the Experts Are Saying

Researchers at ETH Zurich's Computer Vision Lab have been working on perceptual hashing and near-duplicate detection algorithms that could directly address this bottleneck. The lab, based on Rämistrasse 101 in the university quarter, has published methodology applicable to large-scale institutional image databases, and several staff members have held informal consultations with city IT planners, according to publicly available meeting summaries from the Departement der Industriellen Betriebe. No formal procurement contract has been announced, and ETH Zurich has not confirmed a specific partnership agreement as of 4 July 2026.

The Swiss Federal Archives in Bern have taken a different approach, integrating commercial deduplication software into their Digitale Langzeitarchivierung program since early 2024. That model is being watched closely by administrators at the Zentralbibliothek Zürich on Zähringerplatz, whose photograph collections span more than a century of city documentation. Curators there have publicly acknowledged, in a January 2026 blog post on the library's own website, that roughly 12 percent of digitised photographic holdings require some form of duplicate or near-duplicate review — a figure that represents tens of thousands of individual files.

Stadtrat-level politicians have been slower to engage. Planning committees within the Gemeinderat have raised digital infrastructure questions primarily in the context of the Zürich 2035 Digitalstrategie framework, approved in principle in March 2025, but duplicate image management has not appeared as a named budget line in any published municipal account reviewed for this article. Advocates argue that framing the issue as a pure archival housekeeping matter has obscured its real cost implications.

Cost and Practical Stakes

Storage is not free, even in the cloud. Municipal IT procurement documents posted to the city's open-data portal indicate Zurich's public sector paid an average of CHF 0.023 per gigabyte per month for cold-storage archiving under its 2024–2026 framework contracts. Multiply that across an estate of several hundred terabytes — the Stadtarchiv alone holds an estimated 180 terabytes of digitised material as of its last published inventory — and the redundancy overhead becomes material. Independent digital preservation specialists estimate that duplicate rates of 10 to 15 percent in large civic archives are common across European cities, though Zurich has not published its own verified figure.

The pharmaceutical sector, a major Zurich employer with campuses stretching from Schlieren to Altstetten, faces the same challenge internally. Companies in that industry manage enormous volumes of microscopy and clinical imaging data, and several have developed in-house deduplication pipelines that archivists from Stadtarchiv Zürich toured in late 2025 as part of a cross-sector learning exchange organised by digitalswitzerland, the Zurich-based technology advocacy network.

What happens next is likely to depend on the autumn budget round at Stadthaus. If city councillors accept a proposed expansion of the Digitalstrategie operational budget, dedicated tooling for image deduplication could appear as a line item for the first time. Institutions not waiting for that decision — including the Zentralbibliothek and several ETH-affiliated research groups — are already piloting open-source tools internally. For Zurich residents trying to access historical neighbourhood photographs through the city's online portals, a cleaner archive means faster, more accurate search results. The administrative case and the public-interest case, for once, point in the same direction.