Fig. 3.

Illustration of 3DPIs employed in this study. (a) the superimposed stereoscopic 3DPIs of 24 subjects (12- channel [8]); (b) the stereoscopic display of a simulated 3DPI (60 × 60 matrix). The x-axis and the y-axis of a 3D coordinate system define the pulse length along the direction of arterial blood flow while the pulse width corresponds to the pulse width perpendicular to that direction. The normalized z-axis represents the pulse amplitude measured with respect to 1 (violet is 0; red is 1).