Istanbul Confronts a Plague of Duplicate Images in Its Digital Archives — and Falls Behind London and Seoul

Istanbul's municipal digital archive holds tens of thousands of photographs of the city's historic fabric — mosques, hans, waterfront yalıs, street scenes from Balat to Üsküdar — yet a significant portion of that collection is catalogued more than once, sometimes under contradictory labels, sometimes under none at all. The Istanbul Metropolitan Municipality's digital infrastructure team began a formal audit of duplicate image records within the city's heritage database in early 2026, an effort that has exposed just how messy the city's visual memory has become after years of fragmented digitisation drives.

The problem matters now because Turkey's broader push to build earthquake-resilient city records — urgent since the February 2023 Kahramanmaraş disaster — depends on accurate, de-duplicated photographic documentation of existing structures. If a building in the Fatih district appears three times in the archive under three different metadata entries, it is nearly impossible to track whether a post-earthquake inspection has been completed, whether a restoration permit has been issued, or whether demolition has already taken place. Clean image data is, in this context, a structural safety issue as much as a heritage one.

What Istanbul Is Actually Doing

Two institutions are at the centre of the effort. The Istanbul Araştırmaları Enstitüsü (Istanbul Research Institute), based in Beyoğlu, has been running a parallel project to cross-reference its own photographic holdings with those held by the Atatürk Kitaplığı — the city's main municipal library on Millet Caddesi in Fatih — to eliminate redundant scans of the same physical prints. The work is manual as much as algorithmic: staff compare hash values generated from scanned files against a deduplication script, then flag borderline cases for human review. According to the institute's published programme for 2025-2026, the project covers an initial batch of roughly 14,000 images.

The Metropolitan Municipality has separately contracted with a local technology firm to apply perceptual hashing — a technique that detects near-identical images even when file names differ — to the broader GIS-linked photographic layer of its urban planning system. That system feeds into the IBB's public data portal, which as of June 2026 lists over 220,000 georeferenced records tied to the historic peninsula alone.

How Istanbul Compares

London's Victoria and Albert Museum completed a comparable de-duplication exercise for its digital image holdings in 2023, working across a collection of approximately 1.2 million objects. The museum used a combination of open-source perceptual hashing tools and a dedicated metadata review team over an 18-month period. Seoul's Hanok Village Documentation Project, administered by the Seoul Metropolitan Government's urban heritage office, embedded deduplication protocols from the outset when it digitised over 80,000 construction survey photographs between 2021 and 2024 — meaning it largely avoided the retrospective clean-up problem Istanbul now faces.

The difference in approach is telling. London and Seoul both treated image integrity as a precondition for database-building, not an afterthought. Istanbul's situation reflects a structural issue familiar to Turkish cultural institutions: digitisation has happened in waves, often grant-funded and institution-specific, with little coordination between the municipality, the Culture Ministry's regional directorate, and independent foundations such as SALT, which maintains its own archive in Galata. Each institution has digitised what it holds without a shared metadata standard, making cross-institutional deduplication technically and politically complicated.

There is a cost dimension too. Storing duplicate high-resolution image files — many scanned at 400 dpi or above — inflates server costs that fall on already stretched municipal budgets. With the Turkish lira's purchasing power continuing to pressure public IT spending in 2026, the efficiency argument for deduplication has become a financial one as much as an archival one.

The Istanbul Research Institute's project is scheduled to publish its methodology and a summary of results by the end of 2026, which advocates in the heritage sector hope will give other institutions a replicable template. The more immediate test is whether the Metropolitan Municipality's deduplication layer integrates cleanly with its earthquake-preparedness mapping by the time the next mandatory structural survey cycle begins. That work is not optional — the clock is already running.