中文摘要：

提出一种面向DCT 域的扩展SIFT 特征（即D-SIFT 特征）, 以提高JPEG 图像的匹配速度. D-SIFT 特征首先在DCT 域对图像进行不同尺度的高斯滤波, 构建出图像的尺度空间; 然后, 把滤波后的图像划分为大小为2×2 的图像块, 并通过检测出极值图像块来估计关键特征点位置; 最后, 利用当前块周围16×16 个子块的DCT 直流系数来统计主方向, 提取每个极值块的描述子. 实验结果表明, D-SIFT 特征可以有效地提高JPEG 图像的匹配效率.

英文摘要：

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.