The iris image with bad quality will be rejected by the automatic iris recognition system

which will result in the failure of identification or verification. Therefore it is necessary to introduce the quality assessment process of iris images in the phase of image acquisition

which aims to pick out the iris image with high quality from the video sequence captured by the image acquisition device. This paper proposes a fast localization method based on connective region analysis to find out the position of the pupil in an iris image

and then proposes a new iris image quality assessment algorithm which can be divided into two steps. In the first step

the high frequency power of right and left part of the pupil is calculated to find out the undefocused images. And in the second step

the gradient information of the upper region of the pupil is computed to distinguish between the occluded images and unoccluded images. The experimental results indicate that the new algorithm is effective to pick out the iris images with high quality.