Istanbul Battles the Duplicate Image Problem: How the City Stacks Up Against Rome and Amsterdam

Istanbul's municipal digitisation drive has run into a recurring obstacle: thousands of duplicate images clogging the databases used by city planners, heritage conservators and emergency-response teams. The Istanbul Metropolitan Municipality's Geographic Information Systems directorate confirmed this year that its urban asset archive — covering everything from Ottoman-era façades in Sultanahmet to newly built apartment blocks in Başakşehir — contains a significant proportion of redundant photographic records, complicating everything from earthquake-risk assessments to tourism licensing approvals.

The timing matters. Turkey's government accelerated the shift to digital land and building registries after the February 2023 Kahramanmaraş earthquakes exposed how paper-based records slowed damage assessments and insurance claims. Istanbul, sitting on the North Anatolian Fault, is under pressure to keep its building inventory clean and current. A database full of duplicate images is not a minor administrative nuisance — it means field inspectors may be reviewing the same structure twice while missing others entirely.

What Istanbul Is Actually Doing

The municipality's response has centred on two initiatives. First, the Istanbul Deprem Risk Yönetimi projesi — the city's earthquake risk management project — began integrating automated hash-comparison software into its image upload pipeline in early 2025, flagging files that are pixel-identical or near-identical before they enter the master database. Second, the Atatürk Cultural Centre on Taksim Square, which reopened in 2021 after a lengthy renovation, is now being used as a pilot site for a structured re-photographing programme: every publicly accessible surface has been catalogued under a single standardised file-naming protocol, producing a clean reference set against which older duplicate entries can be checked.

The Fatih district office, which oversees the historic peninsula including the Topkapı Palace buffer zone and the Grand Bazaar, has been running a parallel manual audit since March 2026. Staff there cross-reference images submitted by restoration contractors against the central archive, rejecting duplicates at the point of submission rather than after the fact. The process is labour-intensive but has reportedly cut redundant entries in the Fatih sub-database by a meaningful margin, according to municipality communications reviewed by The Daily Istanbul.

How Istanbul Compares to Rome and Amsterdam

Rome's municipal heritage department ran into the same problem on a larger scale when it digitised the Sovrintendenza Capitolina's photographic archive between 2018 and 2022. City archivists there estimated that roughly 30 percent of the initial digital upload consisted of duplicate or near-duplicate images, based on a published audit summary from the project. Rome resolved much of it by contracting an external firm to run perceptual-hash deduplication across the full archive before the database went live for public access in late 2022.

Amsterdam took a different approach. The city's Stadsarchief — the municipal archive — adopted a policy requiring contributing departments to run their own deduplication checks before submitting batches, placing the quality-control burden on the source rather than on a central team. The Stadsarchief has been open about the trade-offs: the policy reduced central processing load but introduced inconsistencies because smaller departments lacked the technical resources to run rigorous checks.

Istanbul's current model sits somewhere between the two. It maintains a central automated filter, as Rome did, but also requires district-level pre-submission checks, as Amsterdam does. Critics within the planning sector argue the hybrid approach risks duplication of effort rather than elimination of it, particularly in resource-constrained district offices outside the city core.

The financial stakes are not trivial. Licences for short-term tourist rentals — a contested issue in neighbourhoods like Beyoğlu and Kadıköy, where Airbnb-style platforms have expanded rapidly — are tied to verified building records. Duplicate or conflicting images in the municipal archive have been cited in at least a handful of licensing disputes before Istanbul's administrative courts in 2025 and 2026, though the court dockets reviewed by this newspaper do not specify exact numbers.

Property owners, architects and contractors who submit images to the metropolitan municipality's e-Belediye portal should expect stricter automated rejection of files that match existing entries. The municipality's technical team has indicated that the hash-comparison layer will be extended to the full citywide archive by the end of 2026. For anyone working on building permits or heritage applications in districts such as Üsküdar or Beşiktaş, re-submitting clean, uniquely named image files — rather than recycling photographs from previous applications — will be the practical difference between a fast approval and a queue.