Istanbul Races to Purge Duplicate Images From Its Digital Heritage Archives — and Other Cities Are Watching

Istanbul's archive managers have a problem that sounds trivial until you try to fix it. Duplicate photographs — the same shot of a Sultanahmet facade ingested twice, three times, sometimes a dozen times across different departmental systems — are estimated to consume a significant share of server capacity inside the Istanbul Metropolitan Municipality's digital infrastructure. The cleanup effort, accelerated after a data-consolidation directive issued by the municipality's information technologies directorate earlier this year, has put Istanbul alongside Rome and Athens as cities now formally auditing their visual heritage records for redundant files.

The timing matters for Istanbul in ways it does not for most cities. After the February 2023 Kahramanmaraş earthquakes killed more than 50,000 people across southern Turkey, municipal authorities here sharply increased the pace of building-condition surveys. Inspectors working in districts like Fatih, Zeytinburnu and Bağcılar generated enormous volumes of photographic documentation — structural close-ups, street-elevation shots, interior damage reports — much of it uploaded through field tablets that lacked deduplication protocols. The result was sprawl: multiple versions of identical images sitting in separate folders, tagged with different metadata, invisible to each other.

What the Duplication Actually Costs

Storage is not free. The Istanbul Metropolitan Municipality's cloud and on-premise hybrid storage contract, renewed in 2024, runs to tens of millions of lira annually, according to procurement documents published on the municipality's public tender portal. Exact current figures were not available at time of publication, but technology officers at comparable European city administrations have publicly stated that duplicate image files can account for between 20 and 35 percent of total media storage consumption in large municipal systems before deduplication tools are deployed.

The Istanbul Archaeological Museums, whose Sultanahmet campus holds one of the world's densest concentrations of artefact photography, began its own deduplication project in March 2025. The museums' digitisation unit works with the Ministry of Culture and Tourism's MUSIS database platform. A similar audit at the Topkapı Palace Museum directorate identified redundant image batches dating to scanning campaigns conducted in the early 2010s, when different contractors used different naming conventions and file-compression standards, creating duplicates that were functionally invisible at the point of upload.

Globally, the comparison cases are instructive. Rome's Sovrintendenza Capitolina launched a deduplication sweep across its Zotero-linked photographic holdings in late 2024 after a European Union–funded digitisation audit flagged the problem across twelve heritage cities. Athens completed a pilot programme at the Acropolis Museum's digital archive in early 2025, using perceptual hashing — a technique that matches images by visual content rather than filename — to collapse roughly 18,000 duplicate files into 6,200 unique records. Istanbul's institutions are now evaluating the same hashing approach.

What Comes Next for Istanbul's Archives

The practical question for Istanbul is which institution leads. The Metropolitan Municipality's BELBIM technology subsidiary, which manages city-wide digital infrastructure from its offices in Seyrantepe, is in discussion with the Culture Ministry's regional directorate about a shared deduplication framework. No formal agreement has been announced. Until one is, the museums and the municipality are running parallel — and occasionally contradictory — cleanup processes.

For city residents and researchers, the immediate effect is friction. Historians working at the Istanbul Research Institute on İstiklal Caddesi, or students accessing the Atatürk Library's digital collections in Taksim, sometimes encounter the same archival image under multiple catalogue numbers, each with slightly different provenance notes. That ambiguity erodes the reliability of the record, particularly for earthquake-preparedness documentation where the identity of a specific building photograph needs to be unambiguous.

The deduplication work is unglamorous and mostly invisible to the public, but its consequences are not. A heritage photograph that exists in twelve slightly different compressed versions is a photograph whose authoritative version nobody can agree on. Istanbul, with its extraordinary density of sites, surveys and ongoing seismic documentation, has more at stake in resolving that question than almost any other city in Europe or the Middle East — and the institutions doing the work know it.