Abstract: The location of a user's head, for purposes such as head tracking or motion input, can be determined. For example, a computing device (e.g., a tablet, mobile phone, etc.) can utilize one or more detectors or other image classifiers to detect the presence objects such as features of the face in images captured by one or more cameras of the computing device. Based on the detected feature(s), the subject technology provides embodiments for detecting a heart rate of the user of the computing device without requiring invasive procedures or addition sensors on the computing device by selecting a region of interest for analyzing color or other image data measurements over a period of time. Changes in color at the select region of interest may be further processed to extract a user's heart rate using techniques described further herein.