Automatic Calculation of the Pupil Response from Digital Video

The calculation of pupil response consists to take the measurement of eye's pupil area under a series of light stimuli. In this article is described a procedure to obtain automatically the pupil response from digital video. First, we obtain each video frame using the free software library Kino; then, the eye's position is found on the initial frames; later, in order to obtain the perimeter's pixels of the pupil, standard image processing techniques are applied to the eye's subimage. Finally, the perimeter is fitted to an ellipse using an direct algebraic algorithm, and the pupil area is approximated with the ellipse area