1. An eye tracking method comprising: capturing image data by an image sensor; determining a region of interest as a subarea or disconnected subareas of said image sensor which is to be read out from said image sensor to perform an eye tracking based on the read out image data; wherein said determining of said region of interest comprises: a) initially reading out only a part of the area of said image sensor; b) searching the image data of said initially read out part for one or more features representing eye and/or head position of a subject to be tracked; c) if said search for one or more features has been successful, determining the region of interest based on the location of the successfully searched one or more features, and d) if said search for one or more features has not been successful, reading out a further part of the area of said image sensor to perform a search for one or more features representing the eye position and/or the head position based on said further part, wherein the further part is different from the initially read out part.