Istanbul's Photo Archive Crisis: The Numbers Driving a City-Wide Duplicate Image Purge

Istanbul's cultural and municipal institutions are sitting on a digital storage crisis measured in terabytes and tens of thousands of files. Across the city's publicly funded image archives — from the Istanbul Metropolitan Municipality's urban planning portal to the documentation systems maintained by the Atatürk Library in Beyoğlu — duplicate and near-duplicate photographs have accumulated for years, inflating storage costs, slowing database queries and undermining the reliability of heritage records that planners, researchers and journalists depend on.

The timing matters. Istanbul is midway through a major push to digitise earthquake-risk assessments of older building stock following the February 2023 Kahramanmaraş disaster, and city engineers need clean, indexed photographic records of tens of thousands of structures in districts like Fatih, Balat and Zeytinburnu. When a single building appears under four different file names in three separate folders — each a slightly different compression of the same JPEG — field teams and analysts lose time and, in some cases, lose confidence in which image is authoritative.

The Scale of the Problem in Numbers

Industry estimates for large municipal databases suggest that between 20 and 40 percent of stored image files are duplicates or near-duplicates — a figure cited repeatedly in digital asset management literature from organisations including the International Council of Museums. Applied to Istanbul's known public-sector photographic holdings, which civic technology advocates have estimated at somewhere north of 2.5 million catalogued images across all municipal departments, that would imply anywhere from 500,000 to one million redundant files consuming server capacity that costs real money to maintain.

Cloud and on-premises storage costs in Turkey have risen sharply alongside broader inflation. Enterprise-grade storage that might have cost a municipal department 800 Turkish lira per terabyte per year in 2021 now runs considerably higher, though exact current procurement figures are subject to tender confidentiality. For the Istanbul Metropolitan Municipality — which operates the city's most expansive civic data infrastructure — the cumulative drag of unmanaged image duplication is a budget line that has become difficult to ignore.

The Istanbul Archaeological Museums, whose collections documentation team operates out of the Sultanahmet campus, faces a related but distinct version of the same problem. Digitisation projects funded across multiple grant cycles — including European Union partnership programs active between 2018 and 2023 — produced overlapping image sets with inconsistent metadata, meaning the same artefact might be catalogued under different accession numbers with photographs that are visually identical but technically different files. Reconciling those records requires staff time that curators describe as a significant drain on capacity, even if museum officials have not put a precise public figure on the hours involved.

Detection Technology and What Comes Next

Perceptual hashing — software that generates a compact digital fingerprint of an image's visual content rather than its file size or name — has become the standard tool for identifying duplicates at scale. Major platforms handling high volumes of visual content began deploying it widely after 2015. Istanbul's municipal IT directorate is understood to be evaluating procurement options for duplicate-detection tooling as part of a broader data governance review, though no contract award has been announced publicly as of July 2026.

For smaller organisations, free and open-source tools already exist. The Rumi Institute cultural centre in Üsküdar, which maintains a photographic record of neighbourhood restoration work along the Bosphorus shoreline, began running its own archive through an open-source perceptual hash library in early 2025 and reduced its working image set by roughly 28 percent, according to information shared at a civic tech event in Kadıköy last autumn. That figure, while drawn from a relatively small collection, illustrates the potential efficiency gains.

The practical advice for any Istanbul institution starting this process is straightforward: audit before you delete. Running a detection pass and flagging duplicates for human review — rather than automating deletion — protects against the accidental loss of images that are visually similar but historically distinct, such as two photographs of the same Galata Tower façade taken decades apart. The numbers driving this problem are large. The solution, for once, is methodical rather than expensive.