Processing images of at least one living being

A method of image processing of a scene with respect to at least one living being having at least one body part, comprising:

• receiving a sequence of digital images representing the scene at successive points in time, each said digital image including a plurality of image parts, each image part including at least one image point, each image point having at least one pixel value;
• analyzing a plurality of image parts of at least one of the digital images so as to determine a set of contiguous image parts having similar characteristics;
• responsive to analyzing so as to determine a set of contiguous image parts, automatically selecting at least one measurement zone, the at least one measurement zone including one or more image points of at least one of said contiguous image parts;
• for at least one measurement zone, generating a signal representative of a time-varying average of the at least one pixel value of selected image points of the measurement zone;
• and
• determining at least one of a presence and a frequency value of at least one peak in a spectrum of the signal corresponding to a frequency of a periodic physiological phenomenon of a living being.