1. An image processing method for determining a motion vector of a interpolated block in a covered/uncovered area of an interpolated picture, the interpolated picture being composed of a plurality of blocks, the image processing method comprising: determining a plurality of motion vector variances corresponding to original motion vectors of a plurality of successive blocks along one dimension in the interpolated picture according to the original motion vectors of the successive blocks, wherein the successive blocks include the interpolated block, and the original motion vectors of the successive blocks are results derived by respective block matching calculations; determining first motion vectors and second motion vectors of the successive blocks according to the motion vector variances, wherein the first motion vector and the second motion vector of one of the successive blocks are the original motion vectors of two blocks located on both sides of a block having a maximum motion vector variance, and for each of the successive blocks, the step of determining the first motion vector and second motion vector comprises: determining the block having the maximum motion vector variance according to the motion vector variances in; determining the original motion vectors of two blocks located on both sides of the block having the maximum motion vector variance; and obtaining the first motion vector and the second motion vector respectively according to the original motion vectors; determining a starting point of the interpolated block according to the first motion vectors and the second motion vectors of the successive blocks; and selecting one of the first motion vector and the second motion vector 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; wherein the covered/uncovered area is a background image area blocked by a foreground object in a picture and not blocked in another picture.