A device for extracting physiological information indicative of at least one vital sign of a subject from detected electromagnetic radiation transmitted through or reflected from a subject comprises an input interface for receiving a data stream of detection data derived from detected electromagnetic radiation transmitted through or reflected from a skin region of a subject. The detection data comprises wavelength-dependent reflection or transmission information in at least two signal channels representative of respective wavelength portions. A signal mixer dynamically mixes the at least two signal channels into at least one mixed signal. A processor derives physiological information indicative of at least one vital sign from the at least one mixed signal, and a controller controls the signal mixer to limit the relative contributions of the at least two signal channels mixed into at least one mixed signal and/or the rate-of-change at which said relative contributions are allowed to dynamically change.
