A method processing an image signal, the method comprising: detecting pixels belonging to an edge in an input image, including subsequent (N-2)-th. (N-1)-th, -th, (N+1)-th, and (N+2)-th pixels; determining a spatial period of change in pixel values; and correcting one or more sub-pixels of the pixel belonging to the edge using a weight allocated according to the determined period; wherein determining the spatial period of change comprises: calculating a first difference F1 between a value P(N-2) of the (N-2)-th pixel and a value P(N-1) of the (N-1)-th pixel, a second difference F2 between the value P(N-1) of the (N-1)-th pixel and a value P of the -th pixel, a third difference F3 between the value P of the -th pixel and a value P(N+1) of the (N+1)-th pixel, and a fourth difference F4 between the value P(N+1) of the (N+1)-th pixel and a value P(N+2) of the (N+2)-th pixel; calculating the results of multiplying F1xF2, F2xF3, and F3xF4; and if F1xF2, F2xF3, and F3xF4 all have negative values, the spatial frequency is determined to be 2 pixels, if F1xF2 has a positive value, F2xF3 has a negative value, and F3xF4 has a positive value, the spatial frequency is determined to be 4 pixels, and if F1xF2 has a positive value, F2xF3 has a positive value, and F3xF4 has a negative value, the spatial frequency is determined to be 6 pixels; and if the spatial frequency is determined to be 2 pixels, the weight of 0 is allocated, if the spatial frequency is determined to be 4 pixels, the weight of 1/16 is allocated, and if the spatial frequency is determined to be 6 pixels, the weight of 1/4 is allocated. detecting pixels belonging to an edge in an input image, including subsequent (N-2)-th. (N-1)-th, -th, (N+1)-th, and (N+2)-th pixels; determining a spatial period of change in pixel values; and correcting one or more sub-pixels of the pixel belonging to the edge using a weight allocated according to the determined period; wherein determining the spatial period of change comprises: calculating a first difference F1 between a value P(N-2) of the (N-2)-th pixel and a value P(N-1) of the (N-1)-th pixel, a second difference F2 between the value P(N-1) of the (N-1)-th pixel and a value P of the -th pixel, a third difference F3 between the value P of the -th pixel and a value P(N+1) of the (N+1)-th pixel, and a fourth difference F4 between the value P(N+1) of the (N+1)-th pixel and a value P(N+2) of the (N+2)-th pixel; calculating the results of multiplying F1xF2, F2xF3, and F3xF4; and if F1xF2, F2xF3, and F3xF4 all have negative values, the spatial frequency is determined to be 2 pixels, if F1xF2 has a positive value, F2xF3 has a negative value, and F3xF4 has a positive value, the spatial frequency is determined to be 4 pixels, and if F1xF2 has a positive value, F2xF3 has a positive value, and F3xF4 has a negative value, the spatial frequency is determined to be 6 pixels; and if the spatial frequency is determined to be 2 pixels, the weight of 0 is allocated, if the spatial frequency is determined to be 4 pixels, the weight of 1/16 is allocated, and if the spatial frequency is determined to be 6 pixels, the weight of 1/4 is allocated. calculating a first difference F1 between a value P(N-2) of the (N-2)-th pixel and a value P(N-1) of the (N-1)-th pixel, a second difference F2 between the value P(N-1) of the (N-1)-th pixel and a value P of the -th pixel, a third difference F3 between the value P of the -th pixel and a value P(N+1) of the (N+1)-th pixel, and a fourth difference F4 between the value P(N+1) of the (N+1)-th pixel and a value P(N+2) of the (N+2)-th pixel; calculating the results of multiplying F1xF2, F2xF3, and F3xF4; and if F1xF2, F2xF3, and F3xF4 all have negative values, the spatial frequency is determined to be 2 pixels, if F1xF2 has a positive value, F2xF3 has a negative value, and F3xF4 has a positive value, the spatial frequency is determined to be 4 pixels, and if F1xF2 has a positive value, F2xF3 has a positive value, and F3xF4 has a negative value, the spatial frequency is determined to be 6 pixels; and if the spatial frequency is determined to be 2 pixels, the weight of 0 is allocated, if the spatial frequency is determined to be 4 pixels, the weight of 1/16 is allocated, and if the spatial frequency is determined to be 6 pixels, the weight of 1/4 is allocated.