Figure 2

Pupil radius measurement sequence. (a) ROI selected manually by the user; the four brighter regions in the image correspond to the IR LEDs light reflected by the retina; (b) Image mask with pixels values set to white in the position of the IR LEDs light reflected; (c) the ROI in (a) with the corresponding white pixels in (b) set to a gray level of 35; (d) result of edge enhancement and scale transformed of (c); (e) pupil edge; and (f) the circle that gives the maximum correlation with the pupil border in (d) over the ROI processed image in (d).