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Face recognition from image sets has numerous real-life applications including recognition from security and surveillance systems, multi-view camera networks and personal albums. An image set is an unordered collection of images (e.g., video frames, images acquired over long term observations and personal albums) which exhibits a wide range of appearance variations. The main focus of the previously developed methods has therefore been to find a suitable representation to optimally model these variations. This paper argues that such a representation could not necessarily encode all of the information contained in the set. The paper, therefore, suggests a different approach which does not resort to a single representation of an image set. Instead, the images of the set are retained in their original form and an efficient classification strategy is developed which extends well-known simple binary classifiers for the task of multi-class image set classification. Unlike existing binary to multi-class extension strategies, which require multiple binary classifiers to be trained over a large number of images, the proposed approach is efficient since it trains only few binary classifiers on very few images. Extensive experiments and comparisons with existing methods show that the proposed approach achieves state of the art performance for image set classification based face and object recognition on a number of challenging datasets.

Inexpensive structured light sensors can capture rich information from indoor scenes, and scene labeling problems provide a compelling opportunity to make use of this information. In this paper we present a novel conditional random field (CRF) model to effectively utilize depth information for semantic labeling of indoor scenes. At the core of the model, we propose a novel and efficient plane detection algorithm which is robust to erroneous depth maps. Our CRF formulation defines local, pairwise and higher order interactions between image pixels. At the local level, we propose a novel scheme to combine energies derived from appearance, depth and geometry-based cues. The proposed local energy also encodes the location of each object class by considering the approximate geometry of a scene. For the pairwise interactions, we learn a boundary measure which defines the spatial discontinuity of object classes across an image. To model higher-order interactions, the proposed energy treats smooth surfaces as cliques and encourages all the pixels on a surface to take the same label. We show that the proposed higher-order energies can be decomposed into pairwise sub-modular energies and efficient inference can be made using the graph-cuts algorithm. We follow a systematic approach which uses structured learning to fine-tune the model parameters. We rigorously test our approach on SUN3D and both versions of the NYU-Depth database. Experimental results show that our work achieves superior performance to state-of-the-art scene labeling techniques.