Prague Tackles Massive Digital Archive Crisis With Duplicate Images Costing Millions

Prague's public institutions collectively store an estimated 40 to 60 percent of their digital image archives as near-identical or outright duplicate files, according to internal assessments circulating among IT departments at several city-funded organisations this spring. The figure sounds abstract until you consider what it costs: server infrastructure for the City of Prague's central data repositories runs into tens of millions of crowns annually, and redundant image data is eating a measurable share of that budget without delivering any public value.

The problem has sharpened this year because Prague City Hall is midway through a broader digitisation push under its Smart Prague 2030 strategy, which commits the municipality to migrating paper and legacy digital records into unified, searchable systems. That migration is exposing just how chaotic image storage has become across departments that accumulated files independently for two decades without common standards.

What the Numbers Actually Look Like

The Prague City Archives on Archivní Street in Letňany processed roughly 1.2 million scanned document images between 2019 and 2024 as part of a records digitisation programme. Librarians and archivists working on the project identified that in some document categories — particularly building permits and land registry records from the 1990s — duplicate scan rates ran as high as 35 percent. That means more than 400,000 individual image files in that single institution alone may be redundant copies created when different staff members scanned the same physical documents without cross-checking existing holdings.

At the Municipal Library of Prague, which operates its main branch on Mariánské náměstí and runs more than 40 branch locations across the city, the digital catalogue contains over 2.8 million images tied to its collections catalogue. A 2024 internal audit flagged that deduplication had never been systematically applied to image assets accumulated since the early 2000s. Storage costs for the library's digital infrastructure rose by approximately 18 percent between 2022 and 2025, a jump the library's annual report attributed partly to unchecked data growth rather than new acquisitions.

The technical definition of a duplicate image matters here. Exact pixel-for-pixel copies are straightforward to detect with checksums. The harder — and far more common — problem is near-duplicates: images scanned at slightly different resolutions, brightness levels or rotation angles from the same physical source. These require more sophisticated perceptual hashing tools to catch, and Prague's institutions have been slow to deploy them at scale. European cities of comparable size, including Vienna and Warsaw, have invested in centralised deduplication pipelines for public-sector image data; Prague has no equivalent programme yet.

The Cleanup Effort Now Underway

The Institute of Planning and Development, based at Vyšehradská 57 in Nusle, began a structured duplicate-image replacement project in January 2026 covering its urban planning photo library. The library holds around 180,000 images documenting Prague's development since the 1970s. Early results from the first phase, covering pre-2000 material, found that roughly 22,000 images — about 12 percent of that tranche — were duplicates or near-duplicates eligible for removal or consolidation. Freeing that storage reduced the active library's footprint by approximately 340 gigabytes.

The cost of doing nothing compounds quickly. Cloud or co-located server storage in the Czech market currently runs between 3,000 and 8,000 CZK per terabyte per year depending on redundancy and access tier. Even at the lower end, hundreds of unnecessary terabytes across city departments translate into hundreds of thousands of crowns wasted every budget cycle.

For Prague residents and civic groups that rely on public image databases — whether researching planning applications in Žižkov, tracing heritage buildings in Vinohrady, or accessing historical photograph collections — the practical consequence of the duplicate problem is slower search results and unreliable catalogue data, because redundant entries clog indexes and return conflicting metadata.

City IT procurement documents published on the Prague City Hall tender portal in March 2026 show a contract tender for deduplication software licensing worth up to 4.2 million CZK, suggesting a centralised solution is at least being formally considered. Whether individual institutions will be required to participate, and on what timeline, has not yet been determined. Institutions that want to get ahead of it can begin with free open-source perceptual hashing tools — several European municipal libraries have published their workflows publicly — while waiting for city-wide standards to arrive.