Non-Contact Pulse Rate Detection Methods Based on Adaptive Projection Plane

For an intuitive understanding of traditional remote photoplethysmography (rPPG), this study categorizes existing algorithms into two main types: spatial vector projection and spatial angle projection in RGB color space. The RGB variation induced by noise (RGBnoise) is visualized in color space and approximated by the raw RGB signal. We propose APON (Adaptive Projection plane Orthogonal to Noise) to suppress artifacts. Two rPPG methods, APON_Vector and APON_Angle, are then developed from this adaptive plane. Comparative experiments on the public databases show that APON_Vector is comparable to state-of-the-art methods like CHROM and POS (achieving an Accuracy of 87.35%), while APON_Angle outperforms other angle projection methods (reducing MAE to 0.78 bpm). The results show that the simple yet effective APON contains significant pulse variation and holds potential for more pulse detection methods.