Istanbul's Digital Archives Are Drowning in Duplicate Images — Here's How the City Stacks Up Against Rome and Barcelona

Istanbul's municipal digital infrastructure holds tens of thousands of photographs — heritage site surveys, urban planning documentation, tourism promotion materials — and a growing share of that archive is redundant. The Istanbul Metropolitan Municipality's digital asset management systems, which feed everything from the IBB Open Data Portal to the official tourism bureau's media library, have been flagged internally as carrying significant volumes of duplicate image files that slow retrieval times, inflate storage costs, and complicate licensing compliance.

The problem has sharpened focus in 2026 because of two converging pressures. First, the post-2023 earthquake retrofit push has generated an enormous new wave of photographic surveys of at-risk buildings across districts like Fatih, Zeytinburnu, and Bağcılar, swamping existing systems. Second, Istanbul's annual visitor numbers have climbed back toward pre-pandemic levels, putting fresh demand on the tourism bureau's image supply chains as travel media outlets, guidebook publishers, and social platforms all draw from the same municipal pools.

What Istanbul Is Actually Doing

The IBB's digital services directorate began piloting a perceptual hashing system — software that generates a compact fingerprint for each image and flags near-identical copies regardless of file format or resolution — across its Bosphorus shoreline documentation archive in early 2026. The pilot covers roughly 14,000 image files catalogued under the Boğaz Koruma Projesi, the protective documentation programme for the European and Asian shoreline districts. Staff at the directorate's offices in Saraçhane have been working through a backlog that reportedly stretches back to 2018, when mass digitisation of older photographic prints began in earnest.

Separately, SALT Research — the independent archive and research centre operating from its Beyoğlu building on İstiklal Caddesi — has been running its own deduplication workflow since 2024 as part of a broader metadata standardisation effort. SALT's collection spans urban photography, architectural records, and press images, and the institution has been more aggressive than the municipality in adopting linked open data standards that make duplicate detection a structural feature rather than a periodic clean-up exercise.

The contrast between those two approaches — reactive municipal cleanup versus proactive institutional design — maps onto a divide visible in other cities worldwide.

Rome and Barcelona Are Further Along

Rome's Archivio Storico Capitolino completed a full deduplication audit of its photographic holdings in 2024, applying the same perceptual hashing logic to a collection of approximately 280,000 digitised images. The project, completed in partnership with a Bologna-based data management firm, reportedly eliminated around 18 percent of stored files as true or near-true duplicates. Barcelona's Institut de Cultura de Barcelona went further, embedding automated deduplication directly into its ingest pipeline at the MUHBA city history museum system in 2023, meaning duplicates are caught before they enter the archive rather than after.

Istanbul's situation is not unusual for a city managing heritage documentation at this scale while simultaneously running active urban reconstruction programmes. Storage costs for the IBB's broader digital estate are denominated in US dollars through international cloud contracts, which means lira depreciation has made every redundant gigabyte measurably more expensive to retain than it was three years ago. With the Turkish lira having lost substantial purchasing power against the dollar since 2021, the fiscal argument for leaner archives has grown harder to ignore.

Municipal procurement rules also slow the adoption of third-party deduplication tools. Unlike Barcelona's Institut, which operates under EU public procurement frameworks that include standardised software licensing pathways, Istanbul's directorate must route technology contracts through national procurement procedures that can extend timelines significantly.

For heritage researchers, photographers, and media organisations that regularly license images from Istanbul's public collections, the practical advice for now is straightforward: cross-reference any material drawn from the IBB Open Data Portal against SALT Research's independently maintained catalogue, which carries cleaner metadata and fewer duplicates. The IBB portal's image holdings are searchable by neighbourhood and date range, but users should expect occasional redundant results until the Saraçhane pilot is extended system-wide, a rollout that the directorate has indicated it is targeting for completion before the end of 2026.