A method for detecting edge pixels in an image plane based on intensity and neutrality of a current pixel is provided. The method includes detecting the edge pixels in the image plane based on predetermined criteria. The predetermined criteria determining whether: (a) a difference between the maximum value and the minimum value of the specified characteristic is greater than or equal to a predetermined threshold; and (b) (i) a difference between a current value and the minimum value of the specified characteristic, or (ii) a difference between a current value and the maximum value of the specified characteristic is greater than or equal to a predetermined threshold. The predetermined thresholds are determined based on intensity and neutrality of the current pixel.