Semi-rPPG: Semi-Supervised Remote Physiological Measurement with Curriculum Pseudo-Labeling

TL;DR

This paper introduces Semi-rPPG, a semi-supervised learning approach that uses curriculum pseudo-labeling and consistency regularization to improve remote physiological measurement from facial videos, especially when labeled data is scarce.

Contribution

The study proposes a novel semi-supervised method combining curriculum pseudo-labeling with SNR criteria and a new consistency regularization for quasi-periodic signals, advancing rPPG measurement.

Findings

Semi-rPPG outperforms classical semi-supervised methods on multiple datasets.

The curriculum pseudo-labeling effectively filters low-quality unlabelled data.

A new semi-supervised benchmark for rPPG learning is established.

Abstract

Remote Photoplethysmography (rPPG) is a promising technique to monitor physiological signals such as heart rate from facial videos. However, the labeled facial videos in this research are challenging to collect. Current rPPG research is mainly based on several small public datasets collected in simple environments, which limits the generalization and scale of the AI models. Semi-supervised methods that leverage a small amount of labeled data and abundant unlabeled data can fill this gap for rPPG learning. In this study, a novel semi-supervised learning method named Semi-rPPG that combines curriculum pseudo-labeling and consistency regularization is proposed to extract intrinsic physiological features from unlabelled data without impairing the model from noises. Specifically, a curriculum pseudo-labeling strategy with signal-to-noise ratio (SNR) criteria is proposed to annotate the unlabelled data while adaptively filtering out the low-quality unlabelled data. Besides, a novel consistency regularization term for quasi-periodic signals is proposed through weak and strong augmented clips. To benefit the research on semi-supervised rPPG measurement, we establish a novel semi-supervised benchmark for rPPG learning through intra-dataset and cross-dataset evaluation on four public datasets. The proposed Semi-rPPG method achieves the best results compared with three classical semi-supervised methods under different protocols. Ablation studies are conducted to prove the effectiveness of the proposed methods.