1. A digital image processing method for detecting human irises in a digital image, comprising the steps of: measuring the red intensity of the pixels in the image; determining the probability that each pixel is an iris based upon the red intensity of the pixel; determining the probability that each pixel is not an iris based upon the red intensity of the pixel; and determining whether each pixel is an iris by analyzing the relationship between the probability that the pixel is an iris and probability that the pixel is not an iris.