Istanbul's Duplicate Image Problem: The Numbers Driving a Digital Reckoning for the City's Archives

Istanbul's public institutions are sitting on a problem measured in terabytes. Across municipal photography archives, tourism promotion databases, and heritage documentation systems, duplicate and near-duplicate images have multiplied to the point where curators and IT administrators are now treating the backlog as a genuine operational crisis. Rough internal assessments circulating within the Istanbul Metropolitan Municipality's digital services directorate put the redundancy rate in certain photographic collections at somewhere between 30 and 45 percent — meaning roughly one in three images stored is a functional copy of another.

The timing matters. Turkey's broader push to digitise cultural assets accelerated sharply after the February 2023 Kahramanmaraş earthquakes, when the destruction of physical records in affected provinces forced a nationwide conversation about backup systems and archival resilience. Istanbul, which sits on the North Anatolian Fault and faces its own seismic reckoning, began accelerating its own digital preservation efforts shortly after. More data went in faster, with less filtering. The result, by mid-2026, is archives bloated with overlapping content.

What the Data Actually Shows

The scale is easiest to understand at the institutional level. The Istanbul Archaeological Museums, which manages collections across three sites including the main complex in Sultanahmet, began a systematic duplicate-detection audit in early 2025. According to publicly available procurement records on the Turkish government's e-ihale portal, the museum group contracted a domestic software firm to process approximately 280,000 digitised catalogue images. Early-stage reports from that project, summarised in a municipal budget presentation reviewed by The Daily Istanbul, flagged that roughly 67,000 images — around 24 percent of the initial batch — were flagged as probable or confirmed duplicates requiring human review before deletion.

The Istanbul Metropolitan Municipality's BELBIM subsidiary, which handles digital infrastructure for city services, has separately been running automated deduplication across tourism-facing content since January 2026. BELBIM's own published quarterly performance indicators from April 2026 show the division processed 1.4 million image files in the first quarter alone. Storage costs for municipal cloud infrastructure, cited in the same report, ran to approximately 2.3 million Turkish lira per month for photographic and video assets — a figure that administrators noted was rising roughly 18 percent year-on-year, tracking broader inflation in cloud service contracts priced partially in US dollars.

For heritage institutions along İstiklal Caddesi and in the Beyoğlu district more broadly, the problem has a specific cultural dimension. The Pera Museum, a private institution, has maintained a digitised archive of its Orientalist painting collection since 2019 and undertook its own deduplication pass in late 2024. Staff have noted publicly in institutional newsletters that high-resolution scans of the same works were often uploaded multiple times under different metadata tags — creating not just storage waste but genuine cataloguing confusion that could mislead researchers.

The Cost of Redundancy, and What Comes Next

Beyond storage bills, duplicates carry a subtler cost: they degrade search accuracy. When a researcher or tourist app queries a visual database and retrieves six slightly different shots of the same Süleymaniye Mosque facade, the practical result is longer load times, lower-quality recommendations, and in some cases the surfacing of lower-resolution or watermark-burdened versions ahead of cleaner ones. For a city that received over 20 million visitors in 2024 according to figures published by the Istanbul Provincial Directorate of Culture and Tourism, the downstream effect on digital visitor experience is not trivial.

The solutions being piloted are primarily algorithmic. Perceptual hashing — a technique that assigns each image a compact numerical fingerprint based on visual content rather than file metadata — is now being tested by at least two Istanbul municipal departments. The method can match near-identical images even when file names, upload dates, and resolution differ. A pilot at the Fatih municipality's local archive service, begun in March 2026, is scheduled to deliver a full deduplication report by September 2026.

For institutions still weighing whether to act, the arithmetic is straightforward. Cloud storage costs in Turkey are unlikely to fall. Lira-denominated contracts tied to dollar-benchmarked services will keep inflating. And every month that passes without systematic deduplication is another month of redundant uploads layering on top of an already unwieldy stack. The window for a clean, low-cost fix is narrowing.