Constrained independent component analysis approach to nonobtrusive pulse rate measurements

• Published in: Journal of Biomedical Optics Vol. 17; no. 7; pp. 770111 - 1-077011-4
• Main Authors: Tsouri, Gill R, Kyal, Survi, Dianat, Sohail, Mestha, Lalit K
• Format: Journal Article
• Language: English
• Published: United States 01.07.2012
• Subjects: Algorithms; Computer Simulation; Constraints; Diagnosis, Computer-Assisted - methods; Errors; Fingers; Heart Rate; Humans; Independent component analysis; Oximetry - methods; Photoplethysmography - methods; Pulse rate; pulse rate estimation; remote sensing; Reproducibility of Results; Sensitivity and Specificity; Sorting; State of the art; Telemedicine - methods
• ISSN: 1083-3668; 1560-2281; 1560-2281
• DOI: 10.1117/1.JBO.17.7.077011

Nonobtrusive pulse rate measurement using a webcam is considered. We demonstrate how state-of-the-art algorithms based on independent component analysis suffer from a sorting problem which hinders their performance, and propose a novel algorithm based on constrained independent component analysis to improve performance. We present how the proposed algorithm extracts a photoplethysmography signal and resolves the sorting problem. In addition, we perform a comparative study between the proposed algorithm and state-of-the-art algorithms over 45 video streams using a finger probe oxymeter for reference measurements. The proposed algorithm provides improved accuracy: the root mean square error is decreased from 20.6 and 9.5 beats per minute (bpm) for existing algorithms to 3.5 bpm for the proposed algorithm. An error of 3.5 bpm is within the inaccuracy expected from the reference measurements. This implies that the proposed algorithm provided performance of equal accuracy to the finger probe oximeter.