The present invention relates to a device and method for processing physiological signals of a subject and in particular to a system for monitoring a (vascular) health parameter of a subject including such a device. The proposed device (10) comprises an input interface (11) for obtaining image data of a scene, said image data comprising a time sequence of image frames； an extraction unit (12) for extracting time-varying signals (92) indicative of cardiac-synchronous motion from said image data, wherein said time-varying signals (92) are motion signals indicative of a vascular micro-motion indicative of a vascular displacement waveform； a polarity determination (13) unit for determining a polarity of the time-varying signals, wherein the polarity corresponds to a phase of the time-varying signals； a combination unit (14) for combining time-varying depending on their polarity to obtain a combination signal； and an analysis unit (15) for determining a (vascular) health parameter based on the combination signal.
