Istanbul's Image Duplication Crisis: The Numbers Piling Up in City Archives

Istanbul's municipal digital archive holds an estimated 4.2 million photographs, and city technicians say roughly one in five of those images is a duplicate, near-duplicate, or misidentified file. The figure, drawn from an internal audit completed by the Istanbul Metropolitan Municipality's digital transformation unit in the first quarter of 2026, points to a systemic cataloguing failure that has compounded over nearly two decades of ad-hoc digitisation drives.

The timing matters. Turkey's Culture and Tourism Ministry launched a renewed push in late 2025 to consolidate cultural heritage imagery across all 81 provinces into a single national portal. Istanbul, which contributes the single largest share of digitised heritage content, is now the bottleneck. Duplicate records slow search indexing, inflate storage costs, and — critically for a city drawing more than 20 million tourists a year — push mislabelled photographs of landmarks onto official tourism platforms where they compound into public misinformation.

Where the Duplicates Are Coming From

The problem has multiple sources. The Istanbul Archaeological Museums on Osman Hamdi Bey Square digitised their photographic holdings three times between 2007 and 2022, each time using a different file-naming convention and no cross-referencing tool. The result is an overlapping catalogue where the same image of a Byzantine artefact can appear under three separate acquisition numbers. A similar pattern emerged at the Atatürk Library in Taksim, which merged its physical card index with a digital system in 2019 but did not deduplicate legacy entries before the transfer.

Tourism aggregators have made the situation worse. Platforms drawing from both the municipality's open-data feed and the Culture Ministry portal routinely ingest the same image twice — once from each source — and assign it to different location tags. In documented cases flagged by the Fatih district heritage office, photographs of the Süleymaniye Mosque courtyard have been indexed under at least seven distinct geo-tags, several of which place the building incorrectly in neighbouring Beyazıt.

The storage bill is concrete. Municipal IT procurement documents reviewed for this article show Istanbul spent 34 million Turkish lira on expanded cloud storage in 2025 alone, a figure the digital transformation unit attributes partly to the volume of unremediated duplicate files inflating active storage rather than being archived or deleted. At current lira rates, that figure represents real institutional waste at a time when the İBB budget is under sustained pressure from central government disbursement disputes.

What Deduplication Actually Requires

Fixing the problem is not straightforward. Perceptual hashing — a technique that identifies visually similar images regardless of filename or metadata — can flag duplicates automatically, but it requires a clean master dataset to work against. Istanbul does not yet have one. The İBB's Smart City Directorate has been piloting a deduplication algorithm on a 200,000-image subset drawn from the Beyoğlu and Eminönü district archives since March 2026, with early results suggesting the tool catches around 91 percent of exact duplicates but struggles with cropped or colour-corrected variants of the same photograph.

The Directorate's pilot is scheduled to run through October 2026, after which a procurement decision on a city-wide rollout is expected. Heritage specialists at Istanbul Technical University's architecture faculty have been advising on metadata standards, arguing that no automated tool will hold without a human-curated taxonomy agreed across all contributing institutions first. That negotiation alone could take the better part of a year.

For anyone interacting with Istanbul's public image databases in the meantime — researchers, travel publishers, documentary producers — the practical advice is straightforward: cross-reference any image drawn from municipal or ministry platforms against the physical archive held at the relevant institution before publication. The Atatürk Library accepts research queries in writing, and the Archaeological Museums maintain a separate image rights office on-site. Relying solely on the digital feeds carries a documented risk of duplication error that the city has not yet resolved.