1. An image interpolating method comprising: detecting an edge direction by calculating absolute inter-channel differences with respect to left, right, up, and down directions of a central pixel of a color filter array according to pattern characteristics of R, G, and B pixels arranged in the color filter array, the absolute inter-channel differences being calculated by subtracting the absolute value of a difference between a color intensity value of a pixel of a first color channel on one side of the central pixel and a color intensity value of a neighboring pixel of a second color channel on the one side of the central pixel, from the absolute value of a difference between a color intensity value of a pixel of the first color channel on a symmetrically opposite side of the central pixel and a color intensity value of a neighboring pixel of the second color channel on the symmetrically opposite side of the central pixel; calculating directional interpolation weights for the left, right, up, and down directions, respectively, according to the pattern characteristics of the R, G, and B pixels; and interpolating an unknown pixel value using color differences between the R, G, and B pixels with respect to the left, right, up, and down directions of the center pixel and the directional interpolation weights according to the detected edge direction.