Detecting Iris Orientation

A method and system for determining a roll angle in an eye image is described. A center of an iris, an inner eye corner, and an outer eye corner in an eye image may be determined. The eye image may be normalized and transformed to a polar eye image using the center of the iris as a reference for the transformation. A shift associated with the inner eye corner and a shift associated with the outer eye corner may be determined. The shifts associated with the inner eye corner and the outer eye corner may be indicators of an orientation of the eye image or roll angle, and may be used for subsequent eye image processing and matching.