Accurate Pupil Detection and Tracking using Modified Circular Hough Transform and IR-EMD

In this paper, a novel method is proposed to detect and to track pupil of one eye using modified
circular Hough transform and a pair of goggles equipped with an infra-red (IR-EMD) camera. The IR-EMD,
which is used in this research, is designed and built after studying several different schemes and despite its
simplicity, it has very good performance and could be thought as one the practical novelties of the project. In
the proposed method for pupil detection, circular Hough transform is used and its speed and accuracy is
enhanced performing several modifications. Applying the modified circular Hough transform to the image
captured with an average quality camera of the IR-EMD, which is also equipped with an IR-LED ring, the
accurate position of the pupil would be detected. In addition to high speed and precision, the algorithm does
not require high quality camera and is robust to the input image noise and some other environmental
parameters such as rotation of the head, eye make-up and background light of the image, as well. Practical
experiments on several people, indicate precision and performance of the proposed algorithm. Besides, in
order to confirm the performance of the algorithm for almost all possible situations, the method is applied to
more than 700 eye images of the CASIA-Iris V.3 database. Results show outstanding performance of the
proposed method. For instance, in presence of pepper and salt noise with 50 percent intensity, the algorithm
could detect the correct position of the pupil of the database images with almost 90 percent accuracy.