Taxonomy Driven Learning Of Semantic Hierarchy Of Classes

Standard pre-trained convolutional neural networks are deployed on different task-specific limited class applications. These applications require classifying images of a much smaller subset of classes than that of the original large domain dataset on which the network is pre-trained. Therefore, a computationally inefficient and over-represented network is obtained. Hierarchically Self Decomposing CNN (HSD-CNN) addresses this issue by dissecting the network into sub-networks in an automated hierarchical fashion such that each sub-network is useful for classifying images of closely related classes. However, visual similarities are not always well-aligned with the semantic understanding of humans. In this paper, we propose a method that aids the pre-trained network to learn the hierarchy of classes derived from standard taxonomy, WordNet and, produce sub-networks corresponding to semantically meaningful classes upon decomposition. Experimental results show that the cluster of classes obtained for each sub-network is semantically closer according to WordNet hierarchy without degradation in overall accuracy.