Distortion-invariant recognition via jittered queries

This paper presents a new approach for achieving distortion-invariant recognition and classification. A test example to be classified is viewed as a query intended to find similar examples in the training set (or to find similar class models that represent a compression of the training set). The key idea is that instead of querying with a single pattern, we construct a more robust query, based on the family of patterns formed by distorting the test example. Although query execution is slower than if the invariances were successfully precompiled during training, there are significant advantages in several contests: (i) providing invariances in memory-based learning, (ii) in model selection, where reducing training time at the expense of test time is a desirable trade-off and (iii) in enabling robust, ad hoc searches based on a single example. Preliminary tests for memory-based learning on the NIST handwritten digit database with a limited set of shearing and translation distortions produced an error rate of 1.35%.