A knowledge-based approach to the iris segmentation problem

This paper describes a knowledge-based approach to the problem of locating and segmenting the iris in images showing close-up human eyes. This approach is inspired in the expert system’s paradigm but, due the specific processing problems associated with image analysis, uses direct encoding of the “decision rules”, instead of a classic, formalized, knowledge base. The algorithm involves a succession of phases that deal with image pre-processing, pupil location, iris location, combination of pupil and iris, eyelids detection, and filtering of reflections. The development was iterative, based on successive improvements tested over a set of training images. The results that were achieved indicate that this global approach can be useful to solve image analysis problems over which human “experts” have better performance than the present computer-based solutions.