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