A method of generating a reliable image of an iris for subsequent optical analysis leading to identification or authentication of a mammal. The method comprises directing point light sources towards the iris, capturing a gray scale image of the iris and reflections of the point light sources, deriving a two tone image from the gray scale image, generating an image containing the true boundaries of the pupil, determining boundaries of the iris and generating an image containing the true boundaries of the iris, and generating a final image of the iris from the image containing the true boundaries of the iris. This establishes a reliable image of the iris. The process may further comprise conducting an identification or authentication process based on optical analysis of the final image of the iris and comparison with a pre-established data corresponding to a person whose identity has been confirmed.