Impact of out-of-focus blur on iris recognition

Iris recognition has expanded from controlled settings to uncontrolled settings (on the move, from a distance) where blur is more likely to be present in the images. More research is needed to quantify the impact of blur on iris recognition. In this paper we study the effect of out-of-focus blur on iris recognition performance from images captured with out-of-focus blur produced at acquisition. A key aspect to this study is that we are able to create a range of blur based on changing focus of the camera during acquisition. We quantify the produced out-of-focus blur based on the Laplacian of Gaussian operator and compare it to the gold standard of the modulation transfer function (MTF) of a calibrated black/white chart. The sharpness measure uses an unsegmented iris images from a video sequence with changing focus and offers a good approximation of the standard MTF. We examined the effect of the 9 blur levels on iris recognition performance. Our results have shown that for moderately blurry images (sharpness at least 50%) the drop in performance does not exceed 5% from the baseline (100% sharpness).