1. A method for locating facial features on a facial area, comprising: locating an eye location, comprising: generating an intensity response map by applying a 3-rectangle filter to pixels in an eye slice from the facial area; applying K-mean clustering to the intensity response map to determine the eye location; locating an eye corner location, comprising: preprocessing pixels in an eye patch from the facial area by applying logarithm transform and grayscale stretching to generate a grayscale eye patch; generating a binary map by binarizing the grayscale eye patch using a threshold based on a histogram of the grayscale eye patch; estimating the eye corner location by averaging coordinates weighted by minimal eigenvalues of spatial gradient matrices in an eye corner search region based on the binary map; locating a mouth corner location, comprising: generating another intensity response map by applying another 3-rectangle filter to pixels in a mouth patch from the facial area; generating another binary map by binarizing the another intensity response map using another threshold based on another histogram of the another intensity response map; locating a chin location, comprising: applying angle constrained gradient analysis to reject locations in a chin search region from the facial area that cannot be the chin location; locating a cheek location, comprising: applying another angle constrained gradient analysis to reject locations in a cheek search region from the facial area that cannot be the cheek location; removing falsely detected cheek location candidates by parabola fitting curves through the chin location and cheek location candidates.