We present an optical encryption method of multiple three-dimensional objects based on multiple interferences and single-pixel digital holography. By modifying the Mach-Zehnder interferometer, the interference of the ...We present an optical encryption method of multiple three-dimensional objects based on multiple interferences and single-pixel digital holography. By modifying the Mach-Zehnder interferometer, the interference of the multiple objects beams and the one reference beam is used to simultaneously encrypt multiple objects into a ciphertext. During decryption, each three-dimensional object can be decrypted independently without having to decrypt other objects. Since the single- pixel digital holography based on compressive sensing theory is introduced, the encrypted data of this method is effectively reduced. In addition, recording fewer encrypted data can greatly reduce the bandwidth of network transmission. Moreover, the compressive sensing essentially serves as a secret key that makes an intruder attack invalid, which means that the system is more secure than the conventional encryption method. Simulation results demonstrate the feasibility of the proposed method and show that the system has good security performance.展开更多
针对红外多目标检测跟踪中目标遮挡问题和算法实时性与准确性难以兼顾的不足,提出一种快速准确且抗遮挡的红外目标检测跟踪算法。在目标检测阶段,提出一种基于RAS(running Average with selectivity)背景更新的中值滤波背景差分算法。...针对红外多目标检测跟踪中目标遮挡问题和算法实时性与准确性难以兼顾的不足,提出一种快速准确且抗遮挡的红外目标检测跟踪算法。在目标检测阶段,提出一种基于RAS(running Average with selectivity)背景更新的中值滤波背景差分算法。该算法采用中值滤波法建立背景图像,通过引入反馈思想与滑动时间窗模型,使背景更新的实时性与鲁棒性得到改善。同时,为了有效解决目标遮挡难题,提出一种像素投影分离算法,通过对粘连目标的投影曲线进行分析来实现粘连目标的分离。在目标跟踪阶段,通过采用滤波加权均值移位算法,从而有效克服红外目标描述信息不足的缺点。同时,将该算法与Kalman滤波融合,最终实现红外多目标的快速准确跟踪。在不同红外测试集上实验结果表明,所提算法的检测率与正确跟踪率分别提高到91.05%、83.78%,运行速度达到32帧/秒,在抗遮挡性、实时性、准确性与鲁棒性等方面均优于现有的主流算法。展开更多
Interferometric synthetic aperture radar(InSAR)has been widely used to measure ground displacements related to geophysical and anthropic activities over the past three decades.Satellite SAR systems use microwave signa...Interferometric synthetic aperture radar(InSAR)has been widely used to measure ground displacements related to geophysical and anthropic activities over the past three decades.Satellite SAR systems use microwave signals that interact with the ionosphere when they travel through it during the imaging processes.In this context,ionospheric variations can significantly contaminate SAR imagery,which in turn affects spaceborne InSAR measurements.This bias also leads to a decrease in the coherence and accuracy of InSAR measurements,especially for the low-frequency SAR systems.In this paper,we give an overview of the latest methods for mitigating the ionospheric contributions in InSAR,including Faraday rotation method,azimuth shift method,and range split-spectrum method,and only focus on the single pair of InSAR interferograms.The current challenges and future perspectives are outlined at the end of this paper.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61405130 and 61320106015)
文摘We present an optical encryption method of multiple three-dimensional objects based on multiple interferences and single-pixel digital holography. By modifying the Mach-Zehnder interferometer, the interference of the multiple objects beams and the one reference beam is used to simultaneously encrypt multiple objects into a ciphertext. During decryption, each three-dimensional object can be decrypted independently without having to decrypt other objects. Since the single- pixel digital holography based on compressive sensing theory is introduced, the encrypted data of this method is effectively reduced. In addition, recording fewer encrypted data can greatly reduce the bandwidth of network transmission. Moreover, the compressive sensing essentially serves as a secret key that makes an intruder attack invalid, which means that the system is more secure than the conventional encryption method. Simulation results demonstrate the feasibility of the proposed method and show that the system has good security performance.
文摘针对红外多目标检测跟踪中目标遮挡问题和算法实时性与准确性难以兼顾的不足,提出一种快速准确且抗遮挡的红外目标检测跟踪算法。在目标检测阶段,提出一种基于RAS(running Average with selectivity)背景更新的中值滤波背景差分算法。该算法采用中值滤波法建立背景图像,通过引入反馈思想与滑动时间窗模型,使背景更新的实时性与鲁棒性得到改善。同时,为了有效解决目标遮挡难题,提出一种像素投影分离算法,通过对粘连目标的投影曲线进行分析来实现粘连目标的分离。在目标跟踪阶段,通过采用滤波加权均值移位算法,从而有效克服红外目标描述信息不足的缺点。同时,将该算法与Kalman滤波融合,最终实现红外多目标的快速准确跟踪。在不同红外测试集上实验结果表明,所提算法的检测率与正确跟踪率分别提高到91.05%、83.78%,运行速度达到32帧/秒,在抗遮挡性、实时性、准确性与鲁棒性等方面均优于现有的主流算法。
基金This work was supported by the National Key Research and Development Program of China(2020YFC1512001)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515011427)+6 种基金the Research Grants Council of the Hong Kong Special Administrative Region(Projects PolyU 152232/17E,PolyU 152164/18Eand PolyU152233/19E)the National NaturalScience Foundation of China(Grants 41790445,41974006,42074040 and 41941019)the Shenzhen Scientific Research and Development Funding Program(Nos.20200807110745001,KQJSCX20180328093453763and20200812164904001)the Department of Education of Guangdong(218KTSCX196)the Fundamental Research Funds for the Central Universities(300102269207)the Research Institute for Sustainable Urban Development(RISUD)(BBWB)the Innovation and Technology Fund of Hong Kong(ITP/019/20LP).
文摘Interferometric synthetic aperture radar(InSAR)has been widely used to measure ground displacements related to geophysical and anthropic activities over the past three decades.Satellite SAR systems use microwave signals that interact with the ionosphere when they travel through it during the imaging processes.In this context,ionospheric variations can significantly contaminate SAR imagery,which in turn affects spaceborne InSAR measurements.This bias also leads to a decrease in the coherence and accuracy of InSAR measurements,especially for the low-frequency SAR systems.In this paper,we give an overview of the latest methods for mitigating the ionospheric contributions in InSAR,including Faraday rotation method,azimuth shift method,and range split-spectrum method,and only focus on the single pair of InSAR interferograms.The current challenges and future perspectives are outlined at the end of this paper.
