1. A method for detecting an eye position in a facial image by using a histogram therefor, wherein the facial image contains a plurality of pixels each of which is represented by a grey level value, the method comprising the steps of: (a) filtering the facial image to thereby obtain a filtered facial image; (b) generating a window within the filtered facial image; (c) extracting a histogram from the window; (d) detecting peaks of the histogram; (e) comparing the number of peaks with 3, wherein if the number is equal to 3, the window is regarded as a candidate window; (f) determining two peaks having a maximum and a minimum pixel values among the three peaks of the candidate window; (g) calculating an A.sub.T of the candidate window, wherein the A.sub.T is a sum of A.sub.MAX and A.sub.MIN, and the A.sub.MAX represents the pixel number in a region enclosing the peak having the maximum pixel value and the A.sub.MIN represents the pixel number in a region enclosing the peak having the minimum pixel value; (h) storing the A.sub.T 's for the candidate windows and corresponding position vectors; and (1) selecting a largest A.sub.T among the stored A.sub.T 's and outputting a corresponding position vector as the eye position.