Eye Tracking System

A method of operating an eye tracking system, the eye tracking system comprising a plurality of light sources that are arranged to illuminate a user's eye when the eye tracking system is in use, the method comprising:

• receiving a first-image of a surface, acquired while the surface is illuminated by a first set of the plurality of light sources;
• receiving a second-image of the surface, acquired while the surface is illuminated by a second set of the plurality of light sources, wherein the second set of light sources is different to the first set of light sources;
• processing the first-image and the second-image to determine an illumination contribution of one or more of the light sources;
• and
• determining light-source-control-signalling for one or more of the light sources based on the determined illumination contribution of the one or more of the light sources, wherein the light-source-control-signalling is for setting the intensity of light provided by the respective light sources when the eye tracking system is in use.

A test rig for an eye tracking system, wherein the eye tracking system comprises a plurality of light sources that are arranged to illuminate a user's eye when the eye tracking system is in use, and wherein the test rig comprises:

• a first surface of known reflectivity for simulating the reflectivity of the user's eye;
• a second surface of known reflectivity, which is less reflective than the reflectivity of the first surface, for simulating the reflectivity of regions of the user's face around their eye;
• and
• a mount for the eye tracking system such that, when the eye tracking system is located in the mount, the plurality of light sources illuminate at least the first surface.