A gray difference-based pre-processing for gaze tracking

In practical applications of gaze tracking systems, because the glasses and accessories often degrade the accuracy of eye detection and gaze tracking, the pre-processing to eliminate these factors is extremely essential for gaze tracking systems. In this paper, a gray difference-based pre-processing scheme is proposed, which utilizes the gray difference between the face, pupils and reflecting points on the cornea to detect the eyes. When the proposed scheme is tested under a cross-ratio-invariant-base gaze tracking system with subjects wearing glasses and accessories, the adaptability and practicality of the test system is improved greatly. The experimental results show that the system can achieve average accuracies of about 0.5 degree in a view field of 14×20×10(cm), which is almost the same as most of commercial gaze tracking systems. That demonstrates the proposed pre-processing scheme is so effective and helpful that it is promising to be adopted into gaze tracking system.