A close face-distance warning system for straightend neck prevention

This paper proposes a close face-distance warning system in order to keep personal computer (PC) user away from to the PC display and to prevent straightened neck during prolong PC usage. The system estimates the distance between the display and the user face (called as face distance) from the user face area that is real-timely measured from captured image with built-in webcam. Haar-like cascade classifier is used for the face detection and tracking from captured image every frame. The face distance is then estimated from the number of pixels of the detected skin color area. The system then shows a pop-up warning message on the display when the face comes close to the display than a limit, in order to promote keeping face away from the display. From 20 test subjects, an experiment of the system implemented on a laptop-PC shows that the face distance was estimated within 9.42% of error at the distance from 25 to 55 cm. It was also found out that neck bend angle (vertical) increased from around 0 to about 40 degrees as the face distance decreased from around 55 to 25 cm. The proposed close face-distance warning system then was effective to prevent straightened neck and reduce neck uncomfortable without loosing work productivity during a long typing work on the PC.