June, 2016

Dropout Distillation

Intern. Conf. on Machine Learning (ICML) 2016
By: Samuel Rota Bulò, Lorenzo Porzi, Peter Kontschieder


Dropout is a popular stochastic regularization technique for deep neural networks that works by randomly dropping (i.e. zeroing) units from the network during training. This randomization process allows to implicitly train an ensemble of exponentially many networks sharing the same parametrization, which should be averaged at test time to deliver the final prediction. A typical workaround for this intractable averaging operation consists in scaling the layers undergoing dropout randomization. This simple rule called standard dropout is efficient, but might degrade the accuracy of the prediction. In this work we introduce a novel approach, coined dropout distillation, that allows us to train a predictor in a way to better approximate the intractable, but preferable, averaging process, while keeping under control its computational efficiency. We are thus able to construct models that are as efficient as standard dropout, or even more efficient, while being more accurate. Experiments on standard benchmark datasets demonstrate the validity of our method, yielding consistent improvements over conventional dropout.

Illustration how Dropout Distillation absorbs information from a deep network previously trained conventional dropout.