Image-registration method, medium, and apparatus

An image-registration apparatus comprising:

• an image-capturing module which obtains a first image and a second image using an image sensor;
• a pyramid-generation module which generates first and second image pyramids based on the first and second images, respectively, by performing sub-sampling which reduces the length and width of each of the first and second images by half;
• a direction-calculation module which determines one of five directions respectively corresponding to (−1, 0), (1, 0), (0, 0), (0, −1), and (0, 1) as an optimal movement direction for a current level of the first and second image pyramids based on two images belonging to the current level;
• a motion-vector-calculation module which updates a motion vector for the current level based on the optimal movement direction for the current level;
• and
• an image-update module which updates a first image belonging to a level directly below the current level based on the updated motion vector for the current level,
• wherein the motion-vector-calculation module respsectively calculates a motion vector for each of a plurality of levels of the first and second image pyramids in an order from an uppermost level to a lowermost level as the current level respectively increments from the uppermost level to the lowermost level.