Delhi's Duplicate Image Problem: How the Capital Stacks Up Against Mumbai, London and Seoul

Delhi's public record system holds tens of thousands of photographs that appear more than once — the same pothole photographed six times, the same Yamuna ghat image filed under three separate project codes, the same heritage structure at Mehrauli Archaeological Park tagged to the wrong restoration scheme. The Municipal Corporation of Delhi acknowledged the problem internally in early 2026 when a routine audit of its GIS-linked infrastructure database found duplicate entries running into the thousands across ward-level asset records.

The timing matters. Delhi Metro Rail Corporation is mid-way through Phase 4 expansion, which involves documenting construction progress, land acquisition records and environmental compliance images across 65 kilometres of new corridor. Duplicate or mismatched photographs in that documentation chain can stall compensation claims, delay clearances from the National Green Tribunal and muddy accountability when contractors dispute site conditions. Officials at the DMRC communications office did not respond to a request for comment before deadline, but the issue has surfaced in internal procurement notices reviewed by this reporter.

What Delhi Is Doing — And What It Isn't

The Delhi government's IT Department launched a deduplication pilot in March 2026 under its Delhi Digital Mission framework, targeting image archives held by three agencies: the Delhi Urban Shelter Improvement Board, the Public Works Department and the Heritage Conservation Committee, which oversees protected sites from Humayun's Tomb to the Coronation Park grounds in north Delhi. The pilot uses perceptual hashing — a technique that generates a fingerprint for each image and flags near-identical copies — rather than the more expensive deep-learning matching systems adopted elsewhere. Budget allocated for the first phase is understood to be modest; procurement documents published on the Delhi government's e-tender portal in April 2026 listed the contract value below ₹50 lakh.

Compare that to Mumbai, where the Brihanmumbai Municipal Corporation began a full image-deduplication exercise across its property tax and slum rehabilitation photo banks in 2024, ultimately contracting a Pune-based firm and running the process across roughly 4.2 million archived images. Seoul's city government went further: its Smart City Data Hub, operational since 2023, mandates hash-checking at the point of upload across all 25 district offices, meaning duplicates are rejected before they enter the system rather than cleaned out retrospectively. London's Ordnance Survey, which supplies base mapping data used by Transport for London and the Greater London Authority, moved to automated duplicate detection across its aerial photography archive in 2022.

Delhi's approach is remedial rather than preventive. Images still enter the PWD asset database without any automated check. The deduplication pilot addresses legacy data, not the incoming stream. That distinction is not trivial: field engineers using the Delhi Integrated Multi-Modal Transit System's reporting app upload hundreds of photographs daily from sites across the city, from Janakpuri in the west to Shahdara in the east, and duplicates accumulate faster than any retrospective audit can clear them.

Why It Matters Beyond Bureaucracy

The practical consequences extend to residents. Under the Pradhan Mantri Awas Yojana-Urban scheme, beneficiary verification in Delhi's resettlement colonies — including large clusters in Bawana and Narela — requires photographic evidence matched to household records. Duplicate images have in documented cases been cited by field supervisors as a reason for benefit delays, according to Right to Information responses filed by housing activists and published on the RTI online portal between January and May 2026.

The Yamuna cleanup programme, politically contested between the AAP-led Delhi government and central agencies including the National Mission for Clean Ganga, also relies on before-and-after photographic records to demonstrate compliance and release funds. Duplicate or misattributed images in those files have become a point of dispute in progress reports submitted to the National Green Tribunal.

For residents and civil society groups pressing accountability claims, the practical advice is straightforward: any RTI application seeking photographic evidence from a Delhi civic agency should explicitly request metadata — file creation dates, GPS coordinates embedded in image EXIF data, and the unique document identification number assigned at upload. That metadata is the only reliable way to distinguish an original record from a copy that has been re-entered under a different project code. The Delhi government's pilot, if it extends beyond its initial three-agency scope before the end of 2026, could eventually make that cross-checking unnecessary. For now, it remains the citizen's best tool.