Biometric authentication techniques

A method, comprising:

• determining, by a computing device, a pseudo-random sequence of image capture modes for a plurality of groups of image captures, wherein each group includes at least captures using a first illumination mode and a second illumination mode, wherein the ordering of the first and second illumination modes for each pair is pseudo-randomly determined;
• receiving, by circuitry of the computing device, image information indicated as being captured by a known camera unit;
• and
• determining, by the circuitry, whether to authorize facial recognition in response to analyzing the image information and determining whether the image information was captured using the pseudo-random sequence of image capture modes.

A non-transitory computer readable storage medium having stored thereon design information that specifies a design of at least a portion of a hardware integrated circuit in a format recognized by a semiconductor fabrication system that is configured to use the design information to produce the circuit according to the design, including:

• one or more processing elements configured to:
• determine a pseudo-random sequence of image capture modes for a plurality of groups of image captures, wherein each group includes a capture using a first illumination mode and a capture using a second illumination mode, wherein the ordering of the first and second illumination modes for each pair is pseudo-randomly determined;
• receive image information for a set of image captures by a camera unit;
• determine whether to authorize facial recognition in response to analyzing the image information and determining whether the image information was captured using the pseudo-random sequence of image capture modes.