An improved SIFT descriptor based on in-out region division

SIFT descriptor is one of the most widely-used local features for image matching. This paper presents an in-out region division method to improve the matching rate and the computational efficiency of SIFT descriptor. The descriptor region composed of pixel blocks around each keypoint is divided into the inner and the outer regions, in which different weights are assigned to the feature vectors. In each pixel block, a low dimensional feature vector is extracted. A bidirectional verification strategy is adopted to determine the keypoint matching. The experimental results show that the proposed method greatly improves the matching rate and the computational efficiency.