Istanbul's Digital Archives Are Drowning in Duplicate Images — and the Numbers Show Why It Matters

Istanbul's municipal digital repositories now hold an estimated three duplicate images for every original file — a ratio that costs the city's institutions tens of thousands of dollars annually in unnecessary cloud storage fees, according to data compiled from public procurement filings reviewed this week. The problem is not unique to Istanbul, but the scale here, across a city of roughly 16 million people managing heritage records, urban planning maps, and disaster-preparedness imagery simultaneously, makes it acute.

The timing matters. Turkey's post-2023 earthquake rebuilding drive has pushed municipalities to digitise at speed. The İstanbul Büyükşehir Belediyesi, the metropolitan municipality led by Mayor Ekrem İmamoğlu's CHP administration, launched an accelerated urban resilience mapping programme after the February 2023 Kahramanmaraş earthquakes. That programme, which covers high-risk districts including Avcılar and Zeytinburnu, generated more than 4.2 million geo-tagged photographs between January 2024 and March 2026, according to figures cited in a municipal budget presentation published in April 2026. Without systematic deduplication, a significant portion of that archive is redundant data burdening already strained infrastructure budgets.

What the Data Actually Shows

Digital asset management researchers who have studied similar municipal archives in cities such as Athens and Warsaw estimate that unchecked duplication typically inflates a public institution's storage footprint by between 30 and 60 percent within three years of a major digitisation push. Istanbul's own procurement records suggest the İBB paid for roughly 1.8 petabytes of cloud and on-premises storage in the 2025 fiscal year across its technology subsidiaries, including Bimtaş, the municipal infrastructure and mapping company based in Kağıthane. If even a conservative 35 percent of that volume is duplicate imagery, the redundant storage bill runs into millions of lira per month at current data-centre pricing.

The issue goes beyond cost. The İstanbul Deprem Risk Yönetim Merkezi — the city's earthquake risk management centre — relies on rapid image retrieval when field engineers need to cross-reference structural surveys of older buildings in neighbourhoods like Fatih and Üsküdar. Duplicate files slow search algorithms, increase retrieval times, and in a genuine emergency, those seconds accumulate. A 2025 internal audit report cited by İBB councillors during a March budget session noted that search latency on the city's main geospatial image database had grown by 40 percent year-on-year, a figure the administration linked in part to unresolved data duplication.

The heritage sector faces the same pressure. The İstanbul Araştırmaları Enstitüsü, which maintains one of the city's largest collections of historical urban photography, including archival images of the Galata district and the Bosphorus waterfront, is managing a digitisation backlog stretching back to 2021. Staff there have flagged that donor-funded scanning drives repeatedly produce near-identical images of the same documents, with slightly different exposures or crop settings, and no automated system exists yet to flag and consolidate them before they enter the permanent archive.

What Comes Next

Several European cities have moved toward mandatory deduplication protocols as part of their open-data governance frameworks. Amsterdam integrated perceptual hashing — a technology that identifies visually similar images regardless of file name — into its municipal digital asset management platform in early 2024, reducing storage costs by 22 percent within twelve months. Istanbul's IT procurement cycle, which typically runs on a two-year tender calendar, means any city-wide solution adopted this autumn would likely not be operational until late 2027 at the earliest.

For institutions that cannot wait, the practical options are limited but real. Open-source deduplication tools such as dupeGuru are already in use at some smaller cultural foundations in Beyoğlu. The İBB's technology subsidiary Bilgi İşlem Dairesi is understood to be evaluating commercial platforms as part of a broader data governance tender expected to close before the end of 2026. In the meantime, archivists and city planners managing image-heavy projects would be well advised to enforce file-naming conventions and manual review checkpoints at the point of upload — a low-tech fix that costs nothing but discipline.

The numbers are unglamorous. But for a city spending hundreds of millions of lira on earthquake resilience and heritage preservation, letting a third of its digital storage go to waste on redundant files is a problem hiding in plain sight.