Conventional training of deep neural networks usually requires a substantial amount of data with expensive human annotations. In this paper, we utilize the idea of meta-learning to explain two very different streams of few-shot learning, i.e., the episodic meta-learning-based and pre-train finetune-based few-shot learning, and form a unified meta-learning framework. In order to improve the generalization power of our framework, we propose a simple yet effective strategy named meta-dropout, which is applied to the transferable knowledge generalized from base categories to novel categories. The proposed strategy can effectively prevent neural units from co-adapting excessively in the meta-training stage. Extensive experiments on the few-shot object detection and few-shot image classification datasets, i.e., Pascal VOC, MS COCO, CUB, and mini-ImageNet, validate the effectiveness of our method.

A machine learning model that generalizes well should obtain low errors on the unseen test examples. Test examples could be understood as perturbations of training examples, which means that if we know how to optimally perturb training examples to simulate test examples, we could achieve better generalization at test time. However, obtaining such perturbation is not possible in standard machine learning frameworks as the distribution of the test data is unknown. To tackle this challenge, we propose a meta-learning framework that learns to perturb the latent features of training examples for generalization. Specifically, we meta-learn a noise generator that will output the optimal noise distribution for latent features across all network layers to obtain low error on the test instances, in an input-dependent manner. Then, the learned noise generator will perturb the training examples of unseen tasks at the meta-test time. We show that our method, Meta-dropout, could be also understood as meta-learning of the variational inference framework for a specific graphical model, and describe its connection to existing regularizers. Finally, we validate Meta-dropout on multiple benchmark datasets for few-shot classification, whose results show that it not only significantly improves the generalization performance of meta-learners but also allows them to obtain fast converegence.