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[IEEE 2018 IEEE 20th International Workshop on Multimedia Signal Processing (MMSP) - Vancouver, BC (2018.8.29-2018.8.31)] 2018 IEEE 20th International Workshop on Multimedia Signal Processing (MMSP) - An Adaptive Bandpass Filter Based on Temporal Spectrogram Analysis for Photoplethysmography Imaging
摘要： Photoplethysmography Imaging (PPGI) in the sense of remote vital sign measurement via camera has attracted high interest in recent years. The non-contact measurement principle allows the use in many health monitoring applications, like monitoring of newborns. Beyond that, there are interesting areas of application in the multimedia sector, such as measuring the reaction to multimedia content or heart rate based liveness detection for multimedia security. The derived signal of a PPGI algorithm is often referred as blood volume pulse signal (BVP). The signal corresponds to the optical signal of blood volume changes in the upper skin layers. Most current approaches use peak detection in frequency spectrum to estimate heart rate from BVP signals. However, we focus on heart rate computation based on beat-to-beat peak detection in time domain. In this paper, we present a method for adaptive bandpass filtering for PPGI based on temporal spectrogram analysis of the BVP signal with a sliding time window. The main goal of this new method is to further improve accuracy of beat-to-beat peak detection in time domain. The approach exploits the analysis of main frequency components of the BVP signal over time, to build a bandpass filter with adaptive cutoff frequencies in order to filter noise and interference. So far, state-of-the-art approaches have usually used fixed cut-off frequencies in the physiologically possible range of heart rate. The novelty of the proposed method lies in its simple but effective solution to reduce the influence of noise and interference in the PPGI signal to improve peak detection for heart rate estimation. We show the improvements applying the adaptive bandpass filter technique to four basic algorithmic approaches of PPGI, namely ICA, Chrominance, POS and 2SR and comparing against current state-of-the-art peak detection approaches. For the evaluation we used a database with videos of 26 subjects in 4 different scenarios, each lasting two minutes.
关键词： Photoplethysmography Imaging,time frequency analysis,signal processing,user reaction,peak detection,remote heart rate estimation,adaptive bandpass filtering
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rome, Italy (2018.6.11-2018.6.13)] 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Feasibility of Photoplethysmography Imaging of the Sole of the Foot
摘要： In photoplethysmography imaging the blood volume pulse is extracted from subtle skin color variations recorded with a camera. In most works, the camera is oriented towards the face or the palm of the hand. Recently, it has been shown that applying contact force to the skin, e.g. through contact with a glass plate, increases signal strength. However, this approach is prohibitive for the face and there are applications where the hands are not accessible. In this paper, we address this issue by applying photoplethysmography imaging to the sole of the foot, which is placed on a glass plate and exposed to controlled illumination. We investigate (1) whether this setup acquires signals with an adequate signal-to-noise ratio and (2) whether the feet can be used as a replacement for the more commonly used hands. Additionally, we analyze (3) whether using a carefully selected pixel subset instead of all pixels improves signal-to-noise ratio. We report on experimental data from N=21 healthy subjects that we make publicly available1. We applied photoplethysmography imaging to the sole of the foot and the palm of the hand and used a commercial ?nger photoplethysmography unit as ground truth. It is problematic that there is no established best practice for signal-to-noise estimation in PPGi research; hence we use ?ve different metrics with three from literature. Additionally, we compare the agreement of these metrics using the experimental data. Our results show that (1) the proposed setup acquires signals with an adequate signal-to-noise ratio, (2) using all pixels from foot videos results in slightly inferior performance compared to the hand, but (3) using pixel subsets improves signal quality at the foot to the level of the hand. These results pave the way for the development of a photoplethysmography imaging setup applied at the sole of the foot for different medical applications.
关键词： photoplethysmography imaging,blood volume pulse,signal-to-noise ratio,medical applications,pixel subset
更新于2025-09-09 09:28:46