How Helsinki's City Archive Ended Up Drowning in Duplicate Images — and What Comes Next

Helsinki's city administration has a duplicate image problem. Thousands of photographs held across municipal digital repositories — spanning the Helsinki City Museum's Finna collections, the urban planning directorate's project archives, and the shared drives used by neighbourhood development teams from Kallio to Laajasalo — exist in multiple copies, often with conflicting metadata, mismatched file names, and no clear record of which version is authoritative. The situation did not emerge overnight. It is the product of at least a decade of incremental digitisation decisions, departmental software migrations, and the absence of a single, enforceable image-management policy across city offices.

The issue matters now because Helsinki is midway through a broader push to open its public records and cultural assets to residents and researchers. The city's Helsinki Open Data portal, launched under the national framework set by Finland's Act on Information Management (laki julkisen hallinnon tiedonhallinnasta), committed municipal bodies to progressively higher standards of data integrity. Duplicate and mislabelled images undermine that commitment directly: a photograph of Töölönlahti bay from 1987 filed under three different dates and two different location tags is not open data in any useful sense.

How the Backlog Built Up

The duplication problem has roots in two distinct eras of city IT policy. During the early 2010s, individual departments at Kaupungintalo — Helsinki's City Hall on Pohjoisesplanadi — were given broad latitude to digitise their own paper archives using whichever scanning software their budgets could accommodate. The Helsinki City Museum, operating from its premises on Sofiankatu, ran its own digitisation programme under the HAM (Helsinki Art Museum) umbrella and fed images into the national Finna.fi discovery interface. Meanwhile, the urban environment division maintained a parallel image library tied to its AutoCAD and GIS workflows. Neither system talked to the other in any structured way.

A 2019 internal audit commissioned by the city's information management unit — whose findings were referenced in a subsequent municipal council discussion paper — identified over 40,000 image files across city servers that shared identical pixel content but carried different filenames or folder paths. The audit covered only a subset of city departments. Subsequent estimates from staff working on the Digihelsinki programme suggested the real figure across all units could be three to four times higher, though no single comprehensive count has been officially published. The Digihelsinki programme, which ran from 2016 through 2022 with funding partly drawn from the city's annual digitalisation budget allocation, was intended to unify such workflows but stopped short of a mandatory image deduplication standard.

What the City Is Doing About It

Since early 2025, the city's data governance team has been piloting a deduplication workflow using perceptual hashing tools applied first to the Helsinki City Museum's photograph collection — an archive of roughly 130,000 images covering Helsinki from the 1860s onward. The pilot is running in parallel with the museum's existing Finna cataloguing work and is being evaluated before any potential rollout to other departments. Staff at the Kallio district service point have also been asked to flag redundant uploads in the city's shared content management system as part of a neighbourhood-level records tidy-up that began in January 2026.

No city-wide mandatory policy is yet in force. The practical consequence for residents trying to use the city's digital archives — whether for heritage research, planning objections, or journalism — is that search results on platforms like Finna.fi can surface the same image multiple times with contradictory information attached to each instance. For a city that will host the 2028 World Design Capital programme and has staked part of its international profile on accessible digital culture, that is an uncomfortable gap between aspiration and reality.

The data governance team is expected to present a full deduplication roadmap to the city executive board before the end of 2026. Residents and researchers who encounter obvious duplicates in the Helsinki City Museum's online collections can already flag them through the feedback form on Finna.fi. Whether the broader fix arrives before Helsinki's digital ambitions outpace its archival housekeeping is, for now, an open administrative question.