1. A method for iris detection at a distance of non-cooperative or cooperative subjects, comprising: capturing an image of a face of a subject; processing the image of the face of the subject to identify an eye region that contains at least one eye of the subject; capturing an image of the identified eye region of the subject using an imaging device; determining a iris rotational orientation relative to the imaging device of the iris of the at least one eye, including determining whether the iris rotational orientation provides a best iris rotational orientation towards the imaging device, the best iris rotational orientation being determined by algorithms that maximize a function that depends on key features of the iris to provide a point of maximization; and re-acquiring an image of the eye region if it is determined that the iris rotational orientation does not provide the best iris rotational orientation towards the imaging device.