Tokyo's War on Duplicate Images: How the City Stacks Up Against Seoul, Singapore and London

Tokyo's two largest public image repositories — the Tokyo Metropolitan Library's digital archive in Minami-Azabu and the metropolitan government's official tourism photo bank, managed through the Tokyo Convention & Visitors Bureau — are both running active deduplication programs this fiscal year, a sign that the problem of redundant and near-identical photography has grown too large to ignore. The push comes as inbound tourist arrivals to Japan surpassed 36 million in 2024, according to the Japan National Tourism Organization, flooding every public and commercial platform with overlapping imagery of Senso-ji, Shibuya Crossing and Tokyo Tower at near-identical angles.

The timing matters. Tokyo's housing market, particularly in Minato and Chuo wards, has seen property listing portals bloat with duplicated interior photographs as agencies list the same units across multiple platforms simultaneously. Meanwhile, the yen's sustained weakness has made Japan an irresistible destination for foreign visitors armed with high-quality smartphone cameras, producing an estimated surge in geotagged uploads to platforms like Google Maps and Instagram that Japanese archivists describe as a cataloguing crisis — though no institution has yet released a precise count of the redundant files involved.

What Tokyo Is Actually Doing

The operational response here is fragmented but real. The National Institute of Informatics, headquartered in Hitotsubashi, Chiyoda Ward, has been developing perceptual hashing tools — software that detects near-identical images even when file sizes or colour profiles differ slightly — since at least 2022. Those tools are now being piloted in cooperation with at least one major city ward office, though the institute has not publicly named the partner. Separately, the Tokyo Metropolitan Archives, located near Ushigome-Yanagimachi in Shinjuku Ward, updated its digital asset management protocol in April 2026 to include automated duplicate flagging before any new image enters the public catalogue.

Real-estate portal Homes.co.jp, one of Japan's largest property listing services with offices in Shibuya, introduced a server-side duplicate detection layer in late 2025, according to a product update notice published on the company's investor relations page. The system flags photographs that share more than 85 percent pixel similarity before agents can complete a new listing submission. It is a blunt instrument, and agents in Nakameguro and Koenji have complained informally in industry newsletters that legitimate re-listings get caught in the filter, but the platform has defended the threshold as a starting point.

Seoul and Singapore Are Further Along

Compared with Seoul and Singapore, Tokyo's approach looks piecemeal. Seoul Metropolitan Government completed a full deduplication audit of its official Smart Seoul Data of Things image archive in 2024 and reduced its stored photograph count by roughly 40 percent in a single pass, a figure the city published in its 2025 digital governance report. Singapore's Infocomm Media Development Authority mandated duplicate-image checks across all government agency websites as part of its Digital Government Blueprint update in 2023, giving agencies 18 months to comply.

London sits somewhere in between. The Greater London Authority's photo library underwent a partial deduplication exercise tied to the 2024 mayoral election rebrand, but Transport for London's own image archive — used for wayfinding and press materials — still carries acknowledged redundancy problems that the agency has deprioritised amid budget pressures.

Tokyo's challenge is structural. Unlike Singapore, which governs a city-state with unified digital infrastructure, Tokyo's 23 special wards each maintain separate procurement processes and IT contracts, making a single top-down mandate difficult to enforce. The metropolitan government can issue guidance, but compliance at ward level is voluntary unless tied to subsidy conditions.

For residents and businesses dealing with the practical side of this — property managers in Sumida Ward relisting apartments, tourism operators updating promotional packs — the near-term advice from digital asset professionals is to adopt perceptual hashing tools such as the open-source pHash library or commercial equivalents before submitting imagery to any public or partner portal. With the 2027 World Athletics Championships in Tokyo already prompting a new wave of official photography commissions, the window to get ahead of the next duplication surge is narrowing fast.