The present invention relates to a device system and a method 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 (14). The device comprises an input interface (30) for receiving a data stream of detection data derived from detected electromagnetic radiation transmitted through or reflected from a skin region of a subject wherein the detection data comprises wavelength dependent reflection or transmission information in at least two signal channels representative of respective wavelength portions a signal mixer (32) for dynamically mixing the at least two signal channels into at least one mixed signal a processor (34) for deriving physiological information indicative of at least one vital sign from the at least one mixed signal and a controller (36) for controlling 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.
