Abstract: A method of performing a measurement of a physiological parameter of a person from a series of images is provided, the method comprising: acquiring a series of images of a person, each image of the series of images including at least a skin exposed region of the person; partitioning at least a portion of each image of the series of images into a plurality of image regions; computing target colour values for each image region of each image of the series of images; determining a signal quality indicator of each of the plurality of image regions for the series of images from the target colour values; classifying the plurality of image regions in accordance with the signal quality indicator which has been determined; and performing a measurement of a physiological parameter of the person using one or more of the plurality of image regions based on a result of the classification.