Using natural class hierarchies in multi-class visual classification

We address the problem of computationally efficient visual classification of objects, and propose a system for solving multi-class problems in domains that have inherent hierarchic structure, such as subclass-superclass-relationships based on visual similarity. Class relationships are used at runtime to select the computationally simplest feature space that allows classification at high level of confidence for each example view. Classification accuracies can then be further improved using rank-order voting over multiple views. Our experimental results show that our system compares favorably to previously published results using a demanding benchmark. The results support the hypothesis that class hierarchies based on visual similarities are feasible and useful in controlling the accuracy vs. speed tradeoffs in classification. (c) 2006 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.