Deep Fisher Networks for Large-Scale Image Classification

As massively parallel computations have become broadly available with modern GPUs, deep architectures trained on very large datasets have risen in popularity. Discriminativelytrained convolutional neural networks, in particular, were recently shown to yield state-of-the-art performance in challenging image classification benchmarkssuch as ImageNet. However, elements of these architectures are similar to standard handcrafted representations used in computer vision. In this paper, we explore the extent of this analogy, proposing a version of the stateof-the-art Fishervector image encoding that can be stacked in multiple layers. This architecture significantly improves on standard Fisher vectors, and obtains competitive results with deep convolutional networks at a smaller computational learning cost. Our hybrid architecture allows us to assess how the performance of a conventional handcrafted image classification pipeline changes with increased depth. We also show that convolutional networks and Fisher vector encodings are complementary in the sense that their combination further improves the accuracy.