An image interpolation method is utilized for performing an interpolation on a source image to obtain a destination image. The image interpolation method includes performing a domain transformation on a plurality of pixels of the source image to generate a plurality of first coefficients and a plurality of second coefficients; respectively determining an data interrelationship degree in at least one direction of each first coefficient to generate a plurality of direction results; performing a first interpolation process on the plurality of first coefficients according to the plurality of direction results to generate a plurality of first destination coefficients; performing a second interpolation process on the plurality of second coefficients to generate a plurality of second destination coefficients; performing a reverse domain transformation on the plurality of first destination coefficients and the plurality of second destination coefficients to obtain the destination image.