A method for life sign monitoring and associated controller is provided. The method includes: obtaining a video signal, performing an activity modeling on the video signal to provide an activity signal, performing a vital sign extraction on the video signal to provide a vital sign, performing a filtering on the vital sign in view of the activity signal to suppress a correlation between the activity signal and the vital sign, and accordingly providing a filtered vital sign and, according to the filtered vital sign and whether the activity signal exceeds an activity threshold range, providing a joint decision for categorizing result of life sign monitoring to one of a plurality of predetermined episodes.
