Improved video-based eye-gaze detection method

IEEE Transactions on Biomedical Engineering, 2013

We have developed a pupil-corneal reflection methodbased gaze detection system, which allows large head movements and achieves easy gaze calibration. This system contains two optical systems consisting of components such as a camera and a nearinfrared light source attached to the camera. The light source has two concentric LED rings with different wavelengths. The inner and outer rings generate bright and dark pupil images, respectively. The pupils are detected from a difference image created by subtracting the bright and dark pupil images. The light source also generates the corneal reflection. The 3-D coordinates of the pupils are determined by the stereo matching method using two optical systems. The vector from the corneal reflection center to the pupil center in the camera image is determined as r. The angle between the line of sight and the line passing through the pupil center and the camera (light source) is denoted as θ. The relationship θ = k |r| is assumed, where k is a constant. The theory implies that head movement of the user is allowed and facilitates the gaze calibration procedure. In the automatic calibration method, k is automatically determined while the user looks around on the PC screen without fixating on any specific calibration target. In the one-point calibration method, the user is asked to fixate on one calibration target at the PC screen in order to correct the difference between the optical and visual axes. In the two-point calibration method, in order to correct the nonlinear relationship between θ and |r|, the user is asked to fixate on two targets. The experimental results show that the three proposed calibration methods improve the precision of gaze detection step by step. In addition, the average gaze error in the visual angle is less than 1 • for the seven head positions of the user.

Eye gaze estimation aims to find the point of gaze which is basically," where we look". Estimating the gaze point plays an important role in many applications with varying usage. Gaze estimation is used in automotive industry to ensure safety. In the field of retail shopping and online marketing gaze estimation is used to analyse the consumer's interest and focus. Gaze estimation is also used for psychological tests and in healthcare for diagnosing some of the neurological disorders. This also has a significant role to play in the field to entertainment. There are multiple ways by which eye gaze estimation can be done. This paper is about a comparative study done on two of the popular methods for gaze estimation using eye features. An infra-red camera is used to capture data for this study. Method 1 tracks corneal reflection centre w.r.t the pupil centre and method 2 tracks the pupil centre w.r.t the eye centre to estimate gaze. There are advantages and disadvantages with both the methods which has been looked into. Choosing the right method for gaze estimation hence depends on the type of application, precision required and many other factors including environmental conditions. This paper can act as a reference for researchers working in the same field

2003

This paper describes a real-time contact-free eye-gaze tracking system that bases its accuracy in a very precise estimation of the pupil centre. The eye camera follows the head movements maintaining the pupil centred in the image. When a tracking error is produced, the image from a camera with a wider field of view is used to locate the eye and quickly recover the tracking process. Four infrared light sources, synchronised with the shutter of the eye camera, are used to produce corneal glints. Its special shape has been exploited to allow the optimisation of the image processing algorithms developed for this system. Special care has been taken in limiting the illumination power and working way below the dangerous levels. After a calibration procedure, the line of gaze is determined by using the pupil-glint vector. The glints are validated using the iris outline with the purpose of avoiding the glint distortion due to the changes in the curvature on the ocular globe. The proposed algorithms determine the pupil centre with sub-pixel resolution, minimising the measurement error in the pupil-glint vector.

Lecture Notes in Computer Science, 2013

We developed a pupil-corneal reflection method-based gaze detection system, which allows head movements and achieves easy gaze calibration. The proposed gaze detection theory determines gaze points on a PC screen from the vector from the corneal reflection to pupil center, 3D pupil position, two cameras position, etc. In a gaze calibration procedure, after a user is asked to gaze one specific calibration target at a center of a PC screen, the nonlinear characteristic of the eyes has been automatically corrected while the user is using this gaze system. The experimental results show that the proposed calibration method improved the precision of gaze detection during browsing web pages. In addition, the average gaze error in the visual angle is less than 0.6 degree for the nine head positions.

Eyes are like window to this large universe. The Advancements in the field of biomedical electronics and in the field of electronics and communication system have changed the perception of eye. People suffering from paralysis do not have sensation to make any motion using hands or legs. It results them of being dependent on others. Failing them being independent .using of joystick cannot be implemented too since they can’t move their hand. It is estimated 150, 00 severely disabled persons able to control only the muscles of their eyes without any problem. Hence using eye gaze we can develop wheelchair that moves on the motion of the eye gaze.

WIT Transactions on Information and Communication Technologies, 1970

For developing a human-computer interface applying eye-gaze, we have already proposed a noncontact, unconstrained video-based pupil detection technique using two light sources and the image difference method. The detected pupil position in the difference image is utilized together with the glint (corneal reflection light of an infrared light source) position for eyegaze position determination. In this paper, the hardware for real-time image differentiation was developed. This image differenciator made realtime pupil possible, by applying the pupil detector including the noise reducer, which had been already developed. For stably detecting the glint and the pupil, it was clarified that the pupil brightness is influenced by the pupil area and the power of infrared light irradiated for the eye. For stabilizing the pupil brightness in the difference images, a method which utilized this characteristics was proposed. This method made pupil and glint center detection stabler.

電子情報通信学会技術研究報告. IE, 画像工学, 2006

An eyegaze interface is one of the key technologies as an input device in the ubiquitous-computing society. In particular, an eyegaze communication system is very important and useful for severely handicapped users such as quadriplegic patients. Most of the conventional eyegaze tracking algorithms require specific light sources, equipment and devices. In this study, a simple eyegaze detection algorithm is proposed using a single monocular video camera. The proposed algorithm works under the condition of fixed head pose, but slight movement of the face is accepted. In our system, we assume that all users have the same eyeball size based on physiological eyeball models. However, we succeed to calibrate the physiologic movement of the eyeball center depending on the gazing direction by approximating it as a change in the eyeball radius. In the gaze detection stage, the iris is extracted from a captured face frame by using the Hough transform. Then, the eyegaze angle is derived by calculating the Euclidean distance of the iris centers between the extracted frame and a reference frame captured in the calibration process. We apply our system to an eyegaze communication interface, and verified the performance through key typing experiments with a visual keyboard on display.

Communications in Computer and Information Science, 2013

In the pupil-corneal reflection detection-based eye-gaze detection method, glasses reflection of near-infrared LED light sources for producing the corneal reflection is misdetected as the pupil when a user wears eyeglasses. To improve the robustness of the pupil detection, we propose novel pupil searching and tracking methods in the gaze detection system using two stereo-calibrated cameras. The pupil searching method first chooses the true pupils from all stereo-matched pupil candidates using the suitable depth range condition, and second chooses the true pair of the right and left pupils under the constraint of the suitable 3-D interpupillary distance. Even if one pupil is not detected in the image of either camera owing to the glasses reflections, the pupil tracking method estimates the 3-D coordinates of the undetected pupil by using the constant interpupillary distance and the temporal continuity of the 3-D coordinates of the moving pupil. The experimental results show that the accuracy of pupil searching and tracking was better than that of the conventional one-camera method.

Communications in Computer and Information Science, 2011

The video-based, head-free, remote eye-gaze detection system based on detection of the pupil and the corneal reflection was developed using stereocalibrated two cameras. The gaze detection theory assumed the linear relationship; θ=k|r'|. Here, θ is the angle between the line of sight and the line connecting between the pupil and the camera, and |r'| indicates the size of the corneal reflection-pupil center vector. Three novel easy calibration methods were proposed; 'automatic', 'one-point', and 'two-point'. In the 'automatic', the user does not have to fixate the specific location in the PC screen. In the 'one-point', the angular difference between the optical and visual axes of the eye was determined and used for compensation. The 'two-point' was proposed to compensate the nonlinear relationship between |r'| and θ, which occurs when θ is large. The precision of gaze detection was compared among the three methods using the developed gaze detection system.

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2001

Video-based eye gaze detection systems are useful for eye-slaved support systems for the severely disabled. The pupil center in the video image is a focal point to determine the eye gaze. Recently, to improve the disadvantages of traditional pupil detection methods, a pupil detection technique using two light sources (LEDs) and the image difference method was proposed. In addition, for users or subjects wearing corrective eyeglasses a method for eliminating the images of the light sources reflected in the glass lens was proposed. However, image-processing hardware for implementing these methods is rather expensive. In the present paper, the hardware construction is replaced by a construction consisting of a combination of a conventional image grabber and a personal computer. An algorithm for windowing around the pupil image with an automatic thresholding method for pupil detection is proposed. The results show that the algorithm works well when the user or the subject is wearing eye...