There is provided a method of extracting a physiological information which comprises, for a defined time-period, extracting a plurality of signal segments in a time-domain form, selecting a subset of the plurality of signal segments according their maximum signal level, converting at least said subset to produce a plurality of transformed signal segments, and combining the at least said subset of the plurality of transformed signal segments to produce a combined signal segment. This has the advantage of reducing the influence of motion and or illumination-induced changes on the final result by removing parts of the raw signal segments which are worst affected by these.
