提出新方法实现面部视频脉搏信号的不确定度量化,提升临床可用性。
Uncertainty-quantified Pulse Signal Recovery from Facial Video using Regularized Stochastic Interpolants
- 将脉搏恢复建模为逆问题,用随机微分方程采样解空间分布
- 在三个数据集上重建精度优于现有方法,且提供可靠不确定度估计
- 适合需可信生理信号输出的医疗与消费级设备应用
基于影像光电容积脉搏波(iPPG)通过摄像头像素值恢复人体血容量脉搏(BVP)波形,是当前热门研究方向。尽管现有算法在基准数据集上表现优异,但尚无先进方法支持测试时对解空间进行采样,无法开展临床关键所需的不确定性分析。为此,本文提出正则化随机插值新范式(RIS-iPPG)。将iPPG恢复视为逆问题,构建随时间演化的概率路径,通过预测瞬时流场和得分向量,从摄像头像素分布逐步逼近真实信号分布;测试时,通过求解随机微分方程采样给定像素测量下正确BVP波形的后验分布。鉴于生理变化缓慢,我们设计正则化策略,最大化相邻时间窗口残差流场预测的相关性,从而提升恢复性能。三组数据集实验表明,RIS-iPPG不仅显著提升重建质量,还提供可靠的不确定性估计,对iPPG在临床及消费场景的广泛应用具有重要意义。
原文摘要 · Abstract (English)
Imaging Photoplethysmography (iPPG), an optical procedure which recovers a human's blood volume pulse (BVP) waveform using pixel readout from a camera, is an exciting research field with many researchers performing clinical studies of iPPG algorithms. While current algorithms to solve the iPPG task have shown outstanding performance on benchmark datasets, no state-of-the art algorithms, to the best of our knowledge, performs test-time sampling of solution space, precluding an uncertainty analysis that is critical for clinical applications. We address this deficiency though a new paradigm named Regularized Interpolants with Stochasticity for iPPG (RIS-iPPG). Modeling iPPG recovery as an inverse problem, we build probability paths that evolve the camera pixel distribution to the ground-truth signal distribution by predicting the instantaneous flow and score vectors of a time-dependent stochastic process; and at test-time, we sample the posterior distribution of the correct BVP waveform given the camera pixel intensity measurements by solving a stochastic differential equation. Given that physiological changes are slowly varying, we show that iPPG recovery can be improved through regularization that maximizes the correlation between the residual flow vector predictions of two adjacent time windows. Experimental results on three datasets show that RIS-iPPG provides superior reconstruction quality and uncertainty estimates of the reconstruction, a critical tool for the widespread adoption of iPPG algorithms in clinical and consumer settings.
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