Iris recognition is an emerging biometric technology for personal identification

whereas iris localization is a crucial part in the process of iris recognition

thus obtaining the iris localization precisely and fleetly is the prelude of effective iris localization . For the purpose of localizing iris precisely

this paper puts forward a novel algorithm of iris localization using block statistic while based on introducing some prevailing algorithms for iris localization. The boundaries that delimit iris can be modeled in a simple way with circular contours. Therefore

the first step in the paper consists of thresholding the iris image intensity to build two binary bitmaps for the succeeding image procession

one for the whole iris and the other for the pupil. The second step is to search for the centroid of the largest block in the iris binary bitmaps by means of Run Length Encoding (RLE)

and calculate the average distance from each point of the boundaries to the centroid obtained before. Experiments show that the algorithm is efficient and successful for the purpose of iris localizing.