An image processing method for determining a motion vector of an interpolated block in a covered/uncovered area of an interpolated picture. The method comprises determining image difference values of successive blocks according to original motion vectors of the successive blocks; determining first and second motion vectors for the successive blocks according to the image difference values, wherein the first and the second motion vector of one of the successive blocks are the original motion vectors of two blocks located in both side of a block having a maximum image difference value; determining a starting point of the interpolated block according to the first and the second motion vectors of the successive blocks; and selecting one of the first and the second motion vectors of the interpolated block as the motion vector of the interpolated block according to the starting point and a starting point in a previous interpolated picture.