Contextually Constrained Deep Networks for Scene Labeling

Learning using deep learning architectures is a difficult problem: the complexity of the prediction model and the difficulty of solving non-convex optimization problems inherent to most learning algorithms can both lead to overfitting phenomena and bad local optima. To overcome these problems we would like to constraint parts of the network using some semantic context to 1) control its capacity while still allowing complex functions to be learned 2) obtain more meaningful layers. We first propose to learn a weak convolutional network which would provide us rough label maps over the neighborhood of a pixel. Then, we incorporate this weak learner in a bigger network. This iterative process aims at increasing the interpretability by constraining some feature maps to learn precise contextual information. Using Stanford and SIFT Flow scene labeling datasets, we show how this contextual knowledge improves accuracy of state-of-the-art architectures. The approach is generic and can be applied to similar networks where contextual cues are available at training time.