2. The method of claim 1 further comprising the step of counting a plurality of numbers of crossing by counting the number of a specific pixel pattern for each of the horizontal coordinates.
2. The method of claim 1 further comprising the step of counting a plurality of numbers of crossing by counting the number of a specific pixel pattern for each of the horizontal coordinates. 3. The method of claim 2 , wherein the pixel pattern is a bright pixel between two dark pixels.