Deep Learning (DL) has shown great promise in the unsupervised task of clustering. That said, while in classical (i.e., non-deep) clustering the benefits of the nonparametric approach are well known, most deep-clustering methods are parametric: namely, they require a predefined and fixed number of clusters, denoted by K. When K is unknown, however, using model-selection criteria to choose its optimal value might become computationally expensive, especially in DL as the training process would have to be repeated numerous times. In this work, we bridge this gap by introducing an effective deep-clustering method that does not require knowing the value of K as it infers it during the learning. Using a split/merge framework, a dynamic architecture that adapts to the changing K, and a novel loss, our proposed method outperforms existing nonparametric methods (both classical and deep ones). While the very few existing deep nonparametric methods lack scalability, we demonstrate ours by being the first to report the performance of such a method on ImageNet. We also demonstrate the importance of inferring K by showing how methods that fix it deteriorate in performance when their assumed K value gets further from the ground-truth one, especially on imbalanced datasets.
This is joint work with Shahaf Finder and Oren Freifeld.
Reference: "DeepDPM: Deep Clustering With an Unknown Number of Clusters" [Meitar Ronen, Shahaf Finder, and Oren Freifeld, CVPR 2022].
Meitar Ronen is a recently-graduated MSc student from BGU CS. She did her research at the Vision, Inference and Learning lab, under Dr. Oren Freifeld's supervision. Her research interests include unsupervised learning, probabilistic models, Bayesian nonparametrics, and Deep Learning. She has authored or co-authored papers published in CVPR 2022, ICCV 2019, and EDM 2019. During her MSc, Meitar won the national VATAT scholarship for outstanding women in the Hi-Tech fields.