Biometric authentication provides the popular way of personal security system. Iris features provides a unique biometric identification in the eye. The eye lids, lashes and flash light impressions are the crucial hazards, during the localization of iris region. The proposed method is used to detect the iris boundary, by eliminating the hazards. The eye image is pre-processed by using the filter with suitable coefficients. The flash noise is eliminated in the pre-processing stage. The morphological operation is imposed on the preprocessed image, which gives out the exact pupil center and area. The pupil boundary is formed by using the pupil center. The horizontal diameter edge points are marked over the pupil region.