1. An image interpolation method, for performing an interpolation on a source image to obtain a destination image, comprising: performing a domain transformation on a plurality of pixels of the source image, for generating a plurality of first coefficients and a plurality of second coefficients corresponding to the plurality of pixels; analyzing and calculating a data correlation degree in at least one direction of each first coefficient according to a plurality of pixel locations of the plurality of pixels, respectively, for generating a plurality of direction results corresponding to the plurality of first coefficients; performing a first interpolation process on the plurality of first coefficients according to the plurality of directional results, for generating a plurality of first destination coefficients; performing a second interpolation process on the plurality of first second coefficients, for generating a plurality of second destination coefficients; and performing an inverse domain transformation on the plurality of first destination coefficients and the plurality of second destination coefficients, for generating the plurality of destination pixels of the destination image.