Whilst contrastive learning has achieved remarkable success in self-supervised representation learning, its potential for deep clustering remains unknown. This is due to its fundamental limitation that the instance discrimination strategy it takes is not class sensitive and hence unable to reason about the underlying decision boundaries between semantic concepts or classes. In this work, we solve this problem by introducing a novel variant called Semantic Contrastive Learning (SCL). It explores the characteristics of both conventional contrastive learning and deep clustering by imposing distance-based cluster structures on unlabelled training data and also introducing a discriminative contrastive loss formulation. For explicitly modelling class boundaries on-the-fly, we further formulate a clustering consistency condition on the two different predictions given by visual similarities and semantic decision boundaries. By advancing implicit representation learning towards explicit understandings of visual semantics, SCL can amplify jointly the strengths of contrastive learning and deep clustering in a unified approach. Extensive experiments show that the proposed model outperforms the state-of-the-art deep clustering methods on six challenging object recognition benchmarks, especially on finer-grained and larger datasets.

本文提出了一种语义对比学习的方法（SCL），将距离的聚类结构引入到无标注数据的特征空间中，并通过优化实例视觉相似性和聚类决策边界的一致性来推理出语义上的实体类别，以在发现未知类别决策边界方面具有显着优势。实验证明，SCL在六个物体识别基准测试中优于最先进的对比学习和深度聚类方法，尤其是在更具挑战性的精细和较大的数据集上。

语义对比学习的深度聚类