Identifying inter-frame forgery is a hot topic in video forensics. In this paper, we propose a method based on the assumption that the correlation coefficients of gray values is consistent in an original video, while ...Identifying inter-frame forgery is a hot topic in video forensics. In this paper, we propose a method based on the assumption that the correlation coefficients of gray values is consistent in an original video, while in forgeries the consistency will be destroyed. We first extract the consistency of correlation coefficients of gray values (CCCoGV for short) after normalization and quantization as distinguishing feature to identify interframe forgeries. Then we test the CCCoGV in a large database with the help of SVM (Support Vector Machine). Experimental results show that the proposed method is efficient in classifying original videos and forgeries. Furthermore, the proposed method performs also pretty well in classifying frame insertion and frame deletion forgeries.展开更多
In view of the low ranging efficiency of the conventional fixed frame-length algorithm in the inter-satellite link,an adaptive frame-length algorithm is proposed. The frame length is adjusted adaptively according to t...In view of the low ranging efficiency of the conventional fixed frame-length algorithm in the inter-satellite link,an adaptive frame-length algorithm is proposed. The frame length is adjusted adaptively according to the results of ranging and velocity measuring to improve ranging efficiency. Buffers which enable the frame length to be selected discretely and adaptively are introduced to avoid frequent hopping of the frame-length.Frame length marker is created to automatically identify the frame-length for frame synchronization procedures in receivers. The feasibility and the validity of the proposed algorithm to improve the efficiency of ranging are verified through both theoretic analysis and simulation,and the efficiency improves up to 88% when there are five buffers. This improvement can be further enhanced by increasing the number of buffers. Proper allocation of inter-satellite buffers is required to make a balance between the ranging efficiency and the system complexity.展开更多
In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by usin...In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by using the high correlation among coding modes and in spatial and temporal domains of video sequence. Simulation results demonstrate that the proposed algorithm can provide significant improvement in computational requirement, with negligible small picture quality degradation and slight bit rate increase.展开更多
Coherent diffraction imaging(CDI)provides lens-free imaging with diffraction-limited resolution and has become an important imaging modality at synchrotron facilities worldwide.The performance of current CDI approache...Coherent diffraction imaging(CDI)provides lens-free imaging with diffraction-limited resolution and has become an important imaging modality at synchrotron facilities worldwide.The performance of current CDI approaches remains limited,particularly in their ability to handle dynamic samples or achieve consistent high-quality reconstructions.Here,we propose a novel coherent imaging approach for dynamic samples,which exploits the inter-frame continuity of the sample’s local structures as an additional constraint in phasing a sequence of diffraction patterns.Our algorithm incorporates an adaptive similarity determination procedure,eliminating the requirement for invariant regions in the sample and ensuring broad applicability to diverse sample types.We demonstrated the feasibility of this technique through experiments on various dynamic samples,achieving high-fidelity reconstructions within a few hundred iterations.With the same simple setup as conventional CDI,high image quality,and the ability to separate the sample transmission from its illumination probe,our method has the potential to significantly advance X-ray imaging and electron microscopy techniques for dynamic sample analysis.展开更多
针对合作靶标特征点成像在大跨度动态测量中的特征提取精度下降、实时性不足问题,提出了一种融合帧间运动预测与改进亚像素边缘检测的自适应光斑质心提取方法。基于合作靶标测量运动连贯性特性,构建了动态感兴趣区域(Region of Interest...针对合作靶标特征点成像在大跨度动态测量中的特征提取精度下降、实时性不足问题,提出了一种融合帧间运动预测与改进亚像素边缘检测的自适应光斑质心提取方法。基于合作靶标测量运动连贯性特性,构建了动态感兴趣区域(Region of Interest,ROI)特征参数模型,以帧间运动预测实现ROI的快速定位,结合大律法阈值优化策略实现自适应Canny边缘检测,在提升计算效率的同时有效解决了不同测量距离下的降噪问题。然后,采用多方向Sobel算子与强度斜坡改进的Zernike矩相结合改进了边缘点定位算法,并基于高斯牛顿迭代改进鲁棒最小二乘圆拟合法,实现质心坐标计算。实验结果表明:在仿真测试中,本方法在不同噪声水平下的质心定位误差为0.001~0.025像素;实际测试中,ROI预测算法可满足加速度8.75 m/s^(2)以内的测量场景需求,10~30 m测量距离内的光斑重复性定位误差稳定在0.016~0.040像素,优于传统方法;光斑提取速度提升约75.5%,显著增强了系统的实时处理能力。本研究可为合作靶标的测量应用提供有效技术保障。展开更多
文摘Identifying inter-frame forgery is a hot topic in video forensics. In this paper, we propose a method based on the assumption that the correlation coefficients of gray values is consistent in an original video, while in forgeries the consistency will be destroyed. We first extract the consistency of correlation coefficients of gray values (CCCoGV for short) after normalization and quantization as distinguishing feature to identify interframe forgeries. Then we test the CCCoGV in a large database with the help of SVM (Support Vector Machine). Experimental results show that the proposed method is efficient in classifying original videos and forgeries. Furthermore, the proposed method performs also pretty well in classifying frame insertion and frame deletion forgeries.
基金Supported by the National High Technology Research and Development Program of China(2013AA1548)
文摘In view of the low ranging efficiency of the conventional fixed frame-length algorithm in the inter-satellite link,an adaptive frame-length algorithm is proposed. The frame length is adjusted adaptively according to the results of ranging and velocity measuring to improve ranging efficiency. Buffers which enable the frame length to be selected discretely and adaptively are introduced to avoid frequent hopping of the frame-length.Frame length marker is created to automatically identify the frame-length for frame synchronization procedures in receivers. The feasibility and the validity of the proposed algorithm to improve the efficiency of ranging are verified through both theoretic analysis and simulation,and the efficiency improves up to 88% when there are five buffers. This improvement can be further enhanced by increasing the number of buffers. Proper allocation of inter-satellite buffers is required to make a balance between the ranging efficiency and the system complexity.
基金National Natural Science Foundation of China (60372018)
文摘In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by using the high correlation among coding modes and in spatial and temporal domains of video sequence. Simulation results demonstrate that the proposed algorithm can provide significant improvement in computational requirement, with negligible small picture quality degradation and slight bit rate increase.
基金supported by the National Natural Science Foundation of China(Grant no.12074167)the Shenzhen Science and Technology Innovation Program(Grant no.JCYJ20241202125334045).
文摘Coherent diffraction imaging(CDI)provides lens-free imaging with diffraction-limited resolution and has become an important imaging modality at synchrotron facilities worldwide.The performance of current CDI approaches remains limited,particularly in their ability to handle dynamic samples or achieve consistent high-quality reconstructions.Here,we propose a novel coherent imaging approach for dynamic samples,which exploits the inter-frame continuity of the sample’s local structures as an additional constraint in phasing a sequence of diffraction patterns.Our algorithm incorporates an adaptive similarity determination procedure,eliminating the requirement for invariant regions in the sample and ensuring broad applicability to diverse sample types.We demonstrated the feasibility of this technique through experiments on various dynamic samples,achieving high-fidelity reconstructions within a few hundred iterations.With the same simple setup as conventional CDI,high image quality,and the ability to separate the sample transmission from its illumination probe,our method has the potential to significantly advance X-ray imaging and electron microscopy techniques for dynamic sample analysis.
文摘针对合作靶标特征点成像在大跨度动态测量中的特征提取精度下降、实时性不足问题,提出了一种融合帧间运动预测与改进亚像素边缘检测的自适应光斑质心提取方法。基于合作靶标测量运动连贯性特性,构建了动态感兴趣区域(Region of Interest,ROI)特征参数模型,以帧间运动预测实现ROI的快速定位,结合大律法阈值优化策略实现自适应Canny边缘检测,在提升计算效率的同时有效解决了不同测量距离下的降噪问题。然后,采用多方向Sobel算子与强度斜坡改进的Zernike矩相结合改进了边缘点定位算法,并基于高斯牛顿迭代改进鲁棒最小二乘圆拟合法,实现质心坐标计算。实验结果表明:在仿真测试中,本方法在不同噪声水平下的质心定位误差为0.001~0.025像素;实际测试中,ROI预测算法可满足加速度8.75 m/s^(2)以内的测量场景需求,10~30 m测量距离内的光斑重复性定位误差稳定在0.016~0.040像素,优于传统方法;光斑提取速度提升约75.5%,显著增强了系统的实时处理能力。本研究可为合作靶标的测量应用提供有效技术保障。
