D-SIFT: an Extended SIFT Feature in the DCT Domain

To accelerate the speed of JPEG image matching, we propose a novel local feature called D-SIFT feature, which is an extension of SIFT in the DCT domain. Firstly, D-SIFT does Gaussian filtering to the image in the DCT domain, obtaining the image scale space. Then, D-SIFT divides all the filtered images into 2×2 image blocks, and estimates all the key points by detecting the key blocks. Finally, D-SIFT obtains the main orientation and extracts the descriptor for each key block from its surrounding 16×16 blocks by using their DC coefficients. Experimental results show that, D-SIFT feature can efficiently improve the speed of JPEG image matching.