The eyegaze communication system is a communication system which is very useful for the blind persons with the help which they can perform their daily activities by using such a communication system. In other words, the Eye tracking is the process of measuring either the point of gaze (where one is looking) or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual system, in psychology, in cognitive linguistics and in product design. There are a number of methods for measuring eye movement. The eyegaze System is a commsunication control system that you can run with your eyes. The Eyegaze System is a direct-select visioncontrolled communication and control system. The motto of this paper clearly deals with the case study of eyegaze communication system.
EYEGAZE SYSTEM WORKING PROCEDURE
As a user sits in front of the eyegaze monitor, a specialized video camera mounted below the monitor observes one of the user's eyes. Sophisticated image- processing software in the eyegaze System's computer continually analyzes the video image of the eye and determines where the user is looking on the screen. Nothing is attached to the user's head or body.
In detail the procedure can be described as follows:
The Eyegaze System uses the pupil-center/cornealreflection method to determine where the user is looking on the screen. As infrared-sensitive video camera, mounted beneath the System’s monitor, takes 60 pictures per second of the user’s eye. A low power, infrared light emitting diode (LED), mounted in the center of the camera’s lens illuminates the eye. The LED reflects a small bit of light off the surface of the eye’s cornea. The light also shines through the pupil and reflects off of the retina, the back surface of the eye, and causes the pupil to appear white. The bright-pupil effect enhances the camera’s image of the pupil and makes it easier for the image processing functions to locate the center of the pupil. The computer calculates the person’s gazepoint, i.e., the coordinates of where he is looking on the screen, based on the relative positions of the pupil center and corneal reflection within the video image of the eye.
Typically the eyegaze System predicts the gazepoint with an average accuracy of a quarter inch or better. Prior to operating, the eye-tracking applications, the eyegaze System must learn several physiological properties of a user’s eye in order to be able to project his gaze-point accurately. The System learns these properties by performing a calibration procedure. The user calibrates the system by fixing his gaze on a small yellow circle displayed on the screen, and following it as it moves around the screen. The calibration procedure usually takes about 15 seconds, and the user does not need to recalibrate if he moves away from the eyegaze System and returns later.
SPECIFICATIONS OF EYEGAZE SYSTEM
This system is robust and extremely easy to calibrate.
System explicitly accommodate several common sources of gaze-point tracking error.
A video camera located below the computer screen remotely and unobtrusively observes the subject’s eye.
No attachments are required to the head.
A small light emitting diode (LED) is located at the center of the camera lens which illuminates the eye. The LED generates the corneal reflection and causes the bright pupil image which enhances the camera’s image of the pupil.
SKILLS REQUIRED FOR USER
Good control of one eye.
Ability to keep his head still in front of the camera.
Some reading or word recognition skill.
