In this paper the gaze tracking system based on the adaptively changing threshold value of the gray level, which automatically detects the pupil position in two dimensional data is proposed. The system detects closed eye using normalized accumulative luminosity function. The detection of closed eye allows the confirmation of voluntary selected command in a more natural way. The presented technique allows recalibration without intervention or help of other assistive persons. Natural head motion is evaluated, employing signals, generated by orientation sensor. Within two experiments, the proposed system is tested at different behavior modes in respect of speed and accuracy of the system.