1. A method for enhancing an image edge, the method comprising: (a) receiving RGB image data; (b) converting the RGB image data into YCbCr data; (c) extracting a first pixel by performing an edge filtering process with respect to Y channel data of the YCbCr data; (d) determining whether a brightness value corresponding to the first pixel is between a first and a second threshold values; (e) applying an N×N (N is an integer number) mask to the first pixel and calculating a maximum value, a minimum value, and a mean value of pixels belonging to the N×N mask if the brightness value is determined to be not between the first and the second threshold values; (f) determining whether a first absolute difference between the minimum value and the mean value is greater than or equal to a third threshold value and whether a second absolute difference between the maximum value and the mean value is greater than or equal to a fourth threshold value; and (g) performing an edge enhancement process with respect to the first pixel according to results of the determination of (f); wherein the first pixel is determined to be on an edge if the brightness value is determined to be between the first and the second threshold values or the first absolute difference is determined to be greater than or equal to the third threshold value and if the second absolute difference is determined to be greater than or equal to the fourth threshold value.