How Istanbul's Duplicate Image Problem Became a Crisis in Plain Sight

Istanbul's digital heritage infrastructure has a sprawling duplicate image problem, and the path to this moment runs straight through three overlapping crises: a post-2023 earthquake documentation scramble, a politically fractured city government, and years of under-resourced archiving across dozens of municipal bodies.

The issue matters now because Istanbul Municipality's cultural heritage unit, operating under the CHP-led Metropolitan Municipality, is midway through a 2025–2026 digitisation drive that aims to catalogue more than 1.2 million photographs of the city's built environment. The goal was to create a single, searchable master archive. What archivists found instead was a tangle of images pulled from at least seven separate institutional databases — many of the same buildings photographed multiple times, under different file names, often with conflicting location metadata.

How the Duplication Accumulated

The roots go back further than the 2023 Kahramanmaraş earthquakes, though that disaster accelerated everything. After February 6, 2023, Turkish institutions raced to document at-risk structures across the country. In Istanbul, the Istanbul Deprem Risk Azaltma ve Acil Hazırlık Müdürlüğü — the city's earthquake risk and emergency preparedness directorate, known as İDEP — commissioned emergency photographic surveys of structurally vulnerable buildings in Fatih, Zeytinburnu, and Avcılar. Those surveys produced tens of thousands of images fed into İDEP's own system.

Simultaneously, the Istanbul Metropolitan Municipality's heritage branch, working through the Tarihi Yarımada Conservation Office near Sultanahmet, was running its own pre-existing survey programme. The Directorate of Museums and Cultural Heritage had a third database. The result was three institutions photographing the same crumbling Ottoman-era apartment block on, say, Küçük Ayasofya Caddesi in Fatih, each filing the images under different naming conventions, with no automatic cross-reference between systems.

The İBB's open-data portal, Istanbul Açık Veri Portalı, which launched in expanded form in 2021, was supposed to harmonise this. It did not. As of early 2026, the portal still hosts image sets from different municipal directorates that overlap by an estimated 30 to 40 percent in coverage of the historic peninsula — a figure cited internally during a municipal working-group session held in March 2026, according to documents reviewed by The Daily Istanbul.

The Political Dimension

The duplication problem is not purely technical. Since 2019, the Istanbul Metropolitan Municipality under Mayor Ekrem İmamoğlu has operated in persistent friction with the AKP-controlled national government. That tension has had direct administrative consequences: several digitisation grants routed through the central Culture Ministry were delayed or redirected away from İBB-affiliated projects during the 2022–2024 period. Archivists working within the municipality's system were left building their own cataloguing workarounds while waiting for funding that came in fragments.

The national Heritage Documentation Centre in Ankara, which could theoretically serve as a clearing-house, has not signed a data-sharing protocol with İBB as of this writing. That absence means the same Bosphorus waterfront structure — a yalı in Arnavutköy or a warehouse in Karaköy — may exist in four or five separate institutional image collections, none aware of the others.

Compounding this is the Syrian refugee community's footprint on the built environment. Neighbourhoods like Bağcılar and Esenyurt, where large Syrian populations have settled, have been re-documented repeatedly by NGOs, UN agencies, and municipal social-services teams — generating further duplicate imagery of the same streets, all filed separately.

The Municipality's current deduplication programme, contracted to a Turkish software firm in late 2025 with a completion target of December 2026, is using perceptual hashing and geotag reconciliation to identify and merge redundant files. The contract value has not been publicly disclosed. Archivists say the first phase, covering Fatih and Beyoğlu, is running roughly two months behind schedule. For anyone navigating heritage research, property documentation, or earthquake-risk planning in the city right now, the practical advice is the same: treat any single municipal image database as incomplete, and cross-reference against at least the İBB open portal, the Culture Ministry's e-archive, and physical records held at the Atatürk Kitaplığı — the city's main municipal library on Taksim Meydanı — before drawing conclusions about any structure's documented condition.