An image signature for any kind of image

We describe an algorithm for computing an image signature, suitable for first-stage screening for duplicate images. Our signature relies on the relative brightness of image regions, and is generally applicable to photographs, text documents, and line art. We give experimental results on the sensitivity and robustness of signatures for actual image collections, and also results on the robustness of signatures under transformations such as resizing, rescanning, and compression.

1. Background and Motivation

Massive image databases are becoming increasingly com-mon. Examples include document image databases such as declassified government documents [8] and photo archives such as the New York Times archive. Duplicate removal offers space and bandwidth savings, and more user-friendly search results. Despite some effort to cull duplicates. the image search service of Google [4] often retrieves a number of duplicate and near-duplicate images. Duplicate detection also finds application in copyright protection and authenti-cation.