1. Introduction
Given a face image as a query, our goal is to retrieve images containing faces of the same person appeared in the query image, from a web-scale image database containing tens of millions face images. Figure 1 shows some example online celebrity face images with various poses, expressions, and illumination. Such a face retrieval system has many applications, including name-based face image search, face tagging in images and videos, copyright enforcement, etc. To the best of our knowledge, little work aims at web-scale face image retrieval. Example online celebrity face images with variances in pose, expression, and illumination.