Istanbul's Duplicate Image Problem: The Numbers Behind a Growing Digital Crisis in the City's Archives

Istanbul's public digital archives contain an estimated 40 to 60 percent rate of duplicate image files across municipal platforms, according to internal assessments described by data management professionals working with city-contracted systems. The figure points to a structural problem that has quietly inflated storage costs, slowed public-facing databases and compromised the integrity of heritage documentation projects running across the city's historic districts.

The timing matters. Istanbul Metropolitan Municipality's digital infrastructure has been under pressure since at least 2023, when post-earthquake surveys in districts like Zeytinburnu and Bağcılar required rapid photographic cataloguing of at-risk building stock. That emergency documentation push — carried out partly under the municipality's Urban Transformation Directorate — generated hundreds of thousands of images in a matter of weeks, with little standardised protocol for deduplication. The result was predictable: the same facade photographed six times under different filenames, stored six times, backed up six times.

Where the Redundancy Accumulates

The problem is not confined to earthquake surveys. The Istanbul Archaeological Museums, which manages collections across three sites including the main complex in Sultanahmet, has long grappled with overlapping digitisation projects funded at different times and by different donors. When the EU-backed Cultural Heritage Digitisation Programme and a separate Turkish Ministry of Culture initiative both targeted the same Ottoman-era artefact collections between 2021 and 2024, coordinators later found that thousands of object photographs had been ingested into the same shared repository under variant naming conventions, producing duplicates that required manual review to resolve.

The tourism sector adds another layer. The Istanbul Convention and Visitors Bureau maintains image libraries used by international travel platforms, and destination marketing organisations routinely ingest the same aerial shots of the Galata Tower or the Bosphorus waterfront from multiple agency sources. A single promotional image of the Golden Horn has been independently tracked appearing under more than 30 distinct file identifiers across publicly accessible Turkish tourism databases, according to a 2025 digital asset audit cited in trade press covering the Türkiye travel marketing sector.

Storage is not cheap. Enterprise-grade cloud storage suitable for high-resolution heritage images runs at roughly 0.02 to 0.05 US dollars per gigabyte per month on major platforms used by Turkish public institutions. A municipal archive carrying 200 terabytes of images — a conservative estimate for a city Istanbul's size — could theoretically cut annual storage expenditure by 30 to 40 percent simply by eliminating confirmed duplicates. For institutions operating under the fiscal strain of lira-denominated budgets during a period of sustained inflation, that is not a trivial sum.

The Technical and Administrative Fix

Deduplication is a solved technical problem. Perceptual hashing algorithms can compare millions of images in hours, flagging near-identical files even when filenames, metadata and compression levels differ. Several Istanbul-based technology firms, including those operating out of the Teknopark Istanbul campus on the Asian side near Pendik, have built bespoke tools for exactly this use case. The barrier is administrative, not computational.

Institutions need clear ownership of their image repositories, agreed retention policies and a single master catalogue rather than the silo-by-silo approach that has characterised most municipal digitisation to date. The Istanbul Metropolitan Municipality's Smart City Directorate has indicated in publicly available planning documents from 2024 that data governance reform is a medium-term priority, but implementation timelines remain unspecified.

For heritage organisations, the practical advice is straightforward: before launching any new digitisation campaign — whether in the covered bazaars of Kapalıçarşı or along the ancient walls of Yedikule — run a baseline duplicate audit first. The cost of doing that work retroactively is almost always higher than preventing the problem at the point of ingestion. Every duplicate image sitting in a government server somewhere in Saraçhane is money that could have gone somewhere more useful.