Method and apparatus for encoding image, and method and apparatus for decoding image based on regularization of motion vector

PURPOSE: An image encoding method based on motion vector normalization and an apparatus thereof, and an encoding method of an image and an apparatus thereof are provided to provide a consistent motion vector field as acquiring the motion vector close to actual motion of the object, by acquiring a larger merged block by merging blocks included in the same object, and predicting the motion vector on the basis of the acquired merged block. CONSTITUTION: A motion prediction and compensation part acquires motion vectors of blocks, and merges two adjacent blocks (910,920). The motion prediction and compensation part acquires a motion vector (930). For the merged block, a block merge part acquires variation of motion prediction error prepared for uniformity of the motion vector by the merging (940). On the basis of the acquired variation, the block merge part determines a merged block which has the smallest variation among the merged blocks, and determines whether to merge the blocks included in the determined merged block (950). [Reference numerals] (910) Acquire the motion vectors of blocks; (920) Merge two adjacent blocks and acquire the merged blocks; (930) Acquire the movement vector of the merged blocks; (940) Acquire the variation of motion prediction errors prepared for uniformity of the motion vector based on the motion vector of the merged blocks, the motion vectors of the blocks contained in the merged block, the motion vectors of the blocks around the merged block, and the motion vectors of the blocks around the blocks contained in the merged block; (950) Determine the merged block which has the smallest variation among the merged blocks based on the acquired variation and determine whether to merge the blocks contained in the determined merged block; (AA) Start; (BB) End