1. Introduction
Deep neural networks have significantly advanced a wide range of computer vision capabilities, including image classification [38], [55], [56], [27], object detection [22], [50], [40], and semantic segmentation [8], [73]. Nonetheless, neural networks typically require massive amounts of manually labeled training data to achieve state-of-the-art performance. Applicability to problems in which labeled data is scarce or expensive to obtain often depends upon the ability to transfer learned representations from related domains.