There is provided a system and method of assessing the quality of the extraction of the signal and the reliability of the physiological measurement by providing a system for producing a quality metric for physiological information extraction from a sequence of image frames, the system comprising a signal extraction unit configured to extract a signal representative of a physiological characteristic from a plurality of the image frames, a signal analyzer configured to calculate a plurality of physiological information results from the signal using a plurality of calculation functions, the plurality of calculation functions being comprised within a list of calculation functions, each physiological information result being calculated using a different calculation function, and a quality metric calculator for calculating a quality metric value based on a signal analysis metric derived from a comparison between the physiological information results of the plurality of physiological information results.