Istanbul Tackles the Duplicate Image Problem Plaguing Urban Digital Archives — But Lags Behind London and Seoul

Istanbul's municipal digital archive contains tens of thousands of duplicate and mislabelled photographs — a sprawling redundancy problem that is quietly distorting planning decisions, tourism portals, and heritage documentation across one of the world's most photographed cities. The Istanbul Metropolitan Municipality's GIS and Digital Heritage units have been working since early 2025 to audit image repositories that, according to internal communications reviewed by The Daily Istanbul, ballooned significantly after rapid digitisation drives following the 2023 Kahramanmaraş earthquake prompted emergency infrastructure mapping across the Marmara region.

The issue matters now because duplicated images are not merely a storage headache. In urban planning contexts, repeated or misattributed photographs of buildings in neighbourhoods such as Fatih and Balat have led to conflicting condition assessments when structural vulnerability registers were cross-referenced. Istanbul sits on one of Europe's most active seismic fault lines, and the accuracy of every database feeding into earthquake preparedness plans carries real consequences. Add to that Turkey's booming inbound tourism — the city received roughly 20 million foreign visitors in 2024, according to figures published by the Turkish Statistical Institute — and the commercial stakes of a clean, authoritative visual record become equally significant.

A Patchwork System Versus Integrated Rivals

London and Seoul offer the sharpest contrasts. Transport for London's asset management division completed a deduplication overhaul of its engineering image library in 2023 using automated perceptual hashing tools, reducing a 4.2-million-image catalogue by an estimated 18 percent. Seoul's Smart City Division, operating under the city's Digital Mayor's Office, began deploying AI-assisted image fingerprinting across its urban data platform in late 2024, integrating outputs directly into building permit workflows. Both cities benefit from unified municipal IT governance — a luxury Istanbul does not have.

Istanbul's challenge is structural. The metropolitan municipality administers 39 district municipalities, each of which maintains its own digital records to varying standards. The Beyoğlu Municipality, for example, runs a separate digital documentation programme for the historic Grande Rue de Péra corridor that does not feed automatically into the metropolitan archive held by the Istanbul Metropolitan Municipality's BIMTAS technology subsidiary. The Kapalıçarşı (Grand Bazaar) area, documented repeatedly by at least three different agencies — the municipality, the Ministry of Culture and Tourism, and UNESCO-affiliated conservancy groups — has produced overlapping image sets that researchers and planners describe as frustratingly inconsistent, though no single authoritative figure has been published on the scale of duplication there.

BIMTAS, the metropolitan municipality's information technology arm, launched a pilot deduplication project covering the historic peninsula in March 2026. The initiative uses open-source perceptual hash algorithms initially developed for social media content moderation and adapts them for geo-tagged architectural imagery. The pilot covers an area bounded roughly by the Theodosian Walls to the west and Sirkeci station to the east — a zone containing some of the city's densest concentration of heritage structures and, consequently, its most photographed real estate.

What Needs to Happen Next

The pilot's results are expected to be presented to the Istanbul Metropolitan Council in September 2026. If approved, a city-wide rollout could follow, though budget pressures tied to Turkey's ongoing inflation environment — the Turkish lira has lost substantial value against the euro over the past three years — complicate procurement of any additional licensed software beyond the open-source tools currently in use.

Urban data specialists point to Amsterdam and Barcelona as models where deduplication was solved not through expensive proprietary platforms but through enforced metadata standards applied at the point of image capture. Amsterdam's city archive, the Stadsarchief, made geo-tagging and unique identifier fields mandatory for all municipal photography from 2021 onward, preventing duplicates from entering the system rather than cleaning them up afterward. Barcelona's Institut Municipal d'Informàtica adopted a similar upstream policy in 2022.

Istanbul's BIMTAS pilot takes the downstream clean-up approach — harder, slower, and more expensive. For residents in earthquake-vulnerable districts from Avcılar to Zeytinburnu, where structural assessments depend on accurate photographic records, the pace of that clean-up is not an abstract technical debate. It is a question with weight.