抗几何攻击的盲检测数字水印的难点是图像旋转角度的盲检测。
It's difficult to detect blindly the image rotation Angle in blind watermarking under geometry attack.
然后以直线特征定义了参考图像和待配准图像的相似性度量，以此度量估计旋转角度，找出直线组的对应关系；
Then define similar measure between the two images by light characteristic, and use this measure to estimate rotated angle and find out corresponding light groups.
摘要 ：改进了传统的尺度不变特征变换（SIFT）算法，使其在进行图像匹配的同时，可以求取出物体的旋转角度。
Abstract : The Scale-invariant Feature Transform(SIFT) algorithm was improved in this paper, which could match two pictures and could also compute the object rotation angles in the pictures.
通过图像旋转的原因分析，推导出普遍适用于航拍图像纠偏处理的公式；并根据无人机飞行姿态来判断航拍图像的旋转角度进而加以纠正，使航拍图像固定指北，有助于操作员正确进行图像的观察及判定。
By correcting the rotating Angle of the image based on the flight attitude of the UAV, the direction of the aerial image can be fixed to help the operator to observe and decide correctly.
对每个可能的匹配对，计算场景中模板图像的位置、尺度变化因子和旋转角度，构成一个4维的投票密度图，则密度最大的地方就是最后的定位结果。
For each match point, the position, scale factor and the rotation angle of the object in scene image can be computed, so the 4d vote space is formed.
本文提出的算法适应性较强，在重复性纹理、旋转角度比较大等较难自动匹配场合下仍可以准确实现图像配准。
In this paper, the algorithm adapted, in the repetitive texture, such as relatively large rotation more difficult to automatically match occasions can still achieve an accurate image registration.
实验结果表明。该算法不仅能够精确定位图像中旋转篡改的区域，而且能估算出区域旋转角度。
Experimental results demonstrate that the proposed approach can not only localize the duplicated regions accurately, but also evaluate the rotation Angle effectively.
实验结果表明。该算法不仅能够精确定位图像中旋转篡改的区域，而且能估算出区域旋转角度。
Experimental results demonstrate that the proposed approach can not only localize the duplicated regions accurately, but also evaluate the rotation Angle effectively.
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