Anytime Recognition with Routing Convolutional Networks.

An automatic trade-off between accuracy and efficiency for a single deep neural network is highly desired in time-sensitive computer vision applications. To achieve anytime prediction, existing methods only embed fixed exits to neural networks and make the predictions with the fixed exits for all the samples. However, it is observed that the latest exit within a time budget does not always provide a more accurate prediction than the earlier exits for testing samples of various difficulties. Motivated by this, we propose to improve the anytime prediction accuracy by allowing each sample to adaptively select its own optimal exit within a specific time budget. Specifically, we propose a new Routing Convolutional Network (RCN). For any given time budget, it adaptively selects the optimal layer as exit for a specific testing sample following the learned policy of the Q-network at the exit, considering both potential information gain and time-cost. The exits and the Q-networks are optimized alternatively to mutually boost each other under the cost-sensitive environment. Apart from anytime image classification, RCN can also be adapted to pixel-wise prediction tasks, e.g., scene parsing. Extensive experimental results on CIFAR-10, CIFAR-100 and ImageNet and Cityscapes benchmarks demonstrate the efficacy of RCN for anytime recognition.