Goto

Collaborating Authors

 beclr


BECLR: Batch Enhanced Contrastive Few-Shot Learning

arXiv.org Artificial Intelligence

Learning quickly from very few labeled samples is a fundamental attribute that separates machines and humans in the era of deep representation learning. Unsupervised few-shot learning (U-FSL) aspires to bridge this gap by discarding the reliance on annotations at training time. Intrigued by the success of contrastive learning approaches in the realm of U-FSL, we structurally approach their shortcomings in both pretraining and downstream inference stages. We propose a novel Dynamic Clustered mEmory (DyCE) module to promote a highly separable latent representation space for enhancing positive sampling at the pretraining phase and infusing implicit class-level insights into unsupervised contrastive learning. We then tackle the, somehow overlooked yet critical, issue of sample bias at the fewshot inference stage. We propose an iterative Optimal Transport-based distribution Alignment (OpTA) strategy and demonstrate that it efficiently addresses the problem, especially in low-shot scenarios where FSL approaches suffer the most from sample bias. We later on discuss that DyCE and OpTA are two intertwined pieces of a novel end-to-end approach (we coin as BECLR), constructively magnifying each other's impact. We then present a suite of extensive quantitative and qualitative experimentation to corroborate that BECLR sets a new state-of-the-art across ALL existing U-FSL benchmarks (to the best of our knowledge), and significantly outperforms the best of the current baselines (codebase available at GitHub). Achieving acceptable performance in deep representation learning comes at the cost of humongous data collection, laborious annotation, and excessive supervision. As we move towards more complex downstream tasks, this becomes increasingly prohibitive; in other words, supervised representation learning simply does not scale. In stark contrast, humans can quickly learn new tasks from a handful of samples, without extensive supervision. Few-shot learning (FSL) aspires to bridge this fundamental gap between humans and machines, using a suite of approaches such as metric learning (Wang et al., 2019; Bateni et al., 2020; Yang Figure 1: FSL has shown promising results in a supervised setting so far on a number of benchmarks (Hu et al., 2022; Singh & Jamali-Rad, 2022; Hu et al., 2023b); however, the need for supervision still lingers on.