1. An image interpolation method for interpolating a pixel, comprising detecting an edge position in an image and obtaining edge characteristics associated with the edge position; determining whether an interpolation point is located within an edge region based on the edge characteristics of an array of p×q pixels surrounding the interpolation point, wherein p and q are integers larger than 1; determining edge direction of an interpolation point located within the edge region; classifying the edge direction into one of m angle subclasses and one of n angle classes; wherein each angle class comprises one or more subclasses, m and n are integers, and n≦m; selecting a one-dimensional horizontal interpolation kernel based on the classified angle class, performing a horizontal interpolation on the interpolation point using the selected one-dimensional horizontal interpolation kernel; and performing a vertical interpolation on the interpolation point using a predetermined one-dimensional vertical interpolation kernel.