The signal evaluation system for detecting the line of sight determines the variation point between 2 signal levels corresponding to the light reflected at the iris and the light reflected at the background of the eye. A threshold level between the 2 signal levels is fixed and 2 bit elements above or below this threshold level are determined, with a line defined by the output levels of this pair of bit elements, or a pair of bit elements with a defined relationship to the latter. A zero transition bit element is obtained from the intersection of this line with the zero level, used to define a second line with a lesser gradient. The variation point is determined from the intersection of the 2 lines. USE - For determining blinking direction of human eye using single-eye mirror reflex camera.
Signal evaluation system for detecting line of sight - detects variation point between two signal levels using defined threshold level