Istanbul's Digital Archives Wrestle With a Flood of Duplicate Images This Week

A cataloguing error that surfaced late last week has left Istanbul's main municipal digitalisation programme with an estimated 14,000 duplicate image files spread across at least three civic archives, sources familiar with the technical review confirmed Friday. The fault — traced to a batch-processing script used during a June upload cycle — affected scanned photographs, architectural drawings and historic maps held by the Istanbul Metropolitan Municipality's digital heritage unit.

The timing is awkward. The municipality has spent much of the past two years racing to digitise physical records ahead of a broader urban-resilience push linked to seismic-preparedness planning following the February 2023 Kahramanmaraş earthquakes. Earthquake-risk assessments for tens of thousands of older buildings in districts like Fatih and Beyoğlu depend partly on archival structural drawings, many of which are now caught up in the deduplication backlog.

Where the Problem Hit Hardest

The Atatürk Library on Yeniçarşı Caddesi in Beyoğlu, which holds one of the city's largest collections of Ottoman-era cadastral maps, has been partially locked out of its own upload portal since Tuesday while technicians run verification checks. Staff there have been reverting to physical files in the interim. The Istanbul Research Institute on İstiklal Caddesi, which maintains a separate but partially linked photographic database covering the city from the 1870s onward, reported on Thursday that roughly 1,200 of its recently ingested images appeared in duplicate or triplicate within the shared repository.

The deduplication work is being handled by the municipality's information technologies directorate in coordination with a contracted software firm based in the Teknopark Istanbul technology campus on the Asian side near Pendik. Engineers have reportedly been running hash-matching algorithms around the clock since Wednesday to identify and flag redundant files without permanently deleting anything — a cautious approach given that some apparent duplicates may differ in resolution or metadata annotation.

At stake is more than archival tidiness. The Istanbul Municipality's digitalisation programme, funded partly through a European Union technical-assistance grant signed in March 2025, has set a contractual milestone requiring a verified, clean image database by September 30 of this year. Missing that date could affect the next tranche of funding under the grant agreement.

What the Deduplication Process Looks Like in Practice

Archivists working with the affected collections describe a painstaking process. Each flagged image must be cross-checked against its physical original or a separately stored master scan before it can be cleared from the redundant-file queue. For the Ottoman cadastral maps held at the Atatürk Library — some dating to the Tanzimat reforms of the mid-19th century — that means pulling fragile originals from climate-controlled storage, a step that can only be performed by a small number of qualified conservators on staff.

The municipality has not yet issued a formal public statement about the scope of the fault, though the issue has circulated within Istanbul's heritage and urban-planning professional community this week. The Istanbul Chamber of Architects, which frequently requests access to archival structural drawings for permit and restoration work, acknowledged informally that access delays had been noticed.

For researchers and planners who rely on the city's growing digital archive, the practical advice right now is straightforward: if you submitted an image-access request after June 20, expect delays of at least two to three weeks while the verification sweep continues. Requests for physical copies, processed through the Atatürk Library's reading-room desk on Yeniçarşı Caddesi, are still being fulfilled on a normal schedule. The Istanbul Research Institute says its own standalone digital catalogue — separate from the shared municipal platform — remains fully operational and accessible via its website.

Technicians at Teknopark Istanbul say they expect the bulk of the automated deduplication pass to be complete by July 11, with manual review of flagged edge cases continuing through the end of the month. Whether the September grant milestone remains achievable will likely become clear only once the full scope of the backlog is mapped — a figure the directorate has said it will release publicly next week.