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

Delhi's municipal and heritage bodies are sitting on a documented backlog of tens of thousands of duplicate digital images — photographs that appear two, three, sometimes a dozen times across government servers — and the process of identifying and replacing them has become an unlikely flashpoint in the city's broader argument over how public records should be managed. The Delhi Urban Heritage Foundation and the Municipal Corporation of Delhi's digital records wing have both flagged the problem in internal reviews conducted over the past eighteen months, according to archivists familiar with the work.

The issue matters now for a specific reason. Delhi Metro Rail Corporation's Phase 4 expansion, which is adding corridors through neighbourhoods including Janakpuri West, R.K. Ashram Marg and Lajpat Nagar, has required fresh environmental and heritage impact surveys. Those surveys draw on photographic databases that, in several cases, contain the same site image filed under multiple reference numbers — creating genuine administrative confusion about whether a site has been photographed once or repeatedly revisited.

The Scale of the Problem in Delhi

The MCD's Geographic Information Systems cell, based out of its Civic Centre headquarters on Minto Road, began a deduplication audit in January 2025. People with knowledge of that process say the initial scan of the public works photography archive turned up a duplication rate of roughly 34 percent across folders dating back to 2009 — the year the three legacy municipal corporations began digitising paper records. That figure has not been formally published, and the MCD has not issued a public statement confirming it, but it has circulated among urban planning professionals in the city.

Compare that to the situation in Mumbai, where the Brihanmumbai Municipal Corporation launched a formal Image Deduplication and Replacement Protocol in March 2024, allocating Rs 1.8 crore to a vendor-led programme that cleared approximately 2.1 lakh redundant files from its Ward Records Management System within eight months. Mumbai's approach was notable for its use of perceptual hashing — a technique that flags visually near-identical images even when file names differ — and for attaching the cleaned archive to a publicly accessible portal at the Bandra Kurla Complex civic office. Delhi has no equivalent public portal as of this writing.

Internationally, the contrast is sharper. Seoul's Smart City Data Hub, which went live in 2022 and is administered through the Seoul Digital Foundation, processes satellite and street-level photographs on a rolling deduplication schedule tied to the city's real-time urban monitoring system. London's Ordnance Survey, working with the Greater London Authority, completed a similar exercise for its 2023 Baseline Environment Survey, deduplicating more than 400,000 georeferenced images over a 14-month period. Both cities publish their methodology openly. Delhi publishes neither its methodology nor its timelines.

What Archivists and Planners Want Next

The practical stakes are not abstract. At Shahjahanabad — the walled city precinct of Old Delhi — the Archaeological Survey of India maintains a photographic record of listed monuments along Chandni Chowk and in the lanes around Jama Masjid. Duplicate entries in that record have, in documented cases, caused surveyors to revisit sites already assessed, wasting field time and distorting damage assessments used to allocate conservation funding. The ASI's Delhi Circle office on Sher Shah Road handles these records; requests for comment on their deduplication schedule were not answered before publication.

The Delhi Urban Heritage Foundation, a non-governmental body that works alongside state heritage committees, has been advocating since 2023 for a unified photographic registry that would allow the MCD, the ASI, the Delhi Development Authority and the DMRC to cross-reference image metadata before filing new photographs. That proposal remains under discussion. No budget line has been publicly allocated for it in the DDA's 2025-26 annual plan, which was tabled in March.

For anyone working with Delhi's public image databases — heritage consultants, journalists filing Right to Information requests, urban researchers at institutions like the School of Planning and Architecture on Indraprastha Estate — the practical advice is straightforward: always cross-check image reference numbers against GPS coordinates before treating a photograph as a unique record. Until Delhi builds what Mumbai and Seoul already have, the duplicate problem is the researcher's problem to manage, not the archive's.