Portmanteau Vocabularies for Multi-Cue Image Representation, Andrew D. Bagdanov

Neural Information Processing Systems 

We describe a novel technique for feature combination in the bag-of-words model of image classification. Our approach builds discriminative compound words from primitive cues learned independently from training images. Our main observation is that modeling joint-cue distributions independently is more statistically robust for typical classification problems than attempting to empirically estimate the dependent, joint-cue distribution directly.