The quaternion Fourier transform plays a vital role in the representation of two-dimensional signals. This paper characterizes spectrum of quaternion-valued signals on the quaternion Fourier transform domain by the pa...The quaternion Fourier transform plays a vital role in the representation of two-dimensional signals. This paper characterizes spectrum of quaternion-valued signals on the quaternion Fourier transform domain by the partial derivative.展开更多
With the improvement of people’s security awareness,numerous monitoring equipment has been put into use,resulting in the explosive growth of surveillance video data.Key frame extraction technology is a paramount tech...With the improvement of people’s security awareness,numerous monitoring equipment has been put into use,resulting in the explosive growth of surveillance video data.Key frame extraction technology is a paramount technology for improving video storage efficiency and enhancing the accuracy of video retrieval.It can extract key frame sets that can express video content from massive videos.However,the existing key frame extraction algorithms of surveillance video still have deficiencies,such as the destruction of image information integrity and the inability to extract key frames accurately.To this end,this paper proposes a key frame extraction algorithm of surveillance video based on quaternion Fourier saliency detection.Firstly,the algorithm used colors,and intensity features to perform quaternion Fourier transform on surveillance video sequences.Next,the phase spectrum of the quaternion Fourier transformed image was obtained,and he image visual saliency map was obtained according to the quaternion Fourier phase spectrum.Then,the image visual saliency map of two adjacent frames is used to characterize the change of target motion state.Finally,the frames that can accurately express the motion state of the target are selected as key frames.The experimental results show that the method proposed in this paper can accurately capture the changes of the local motion state of the target while maintaining the integrity of the image information.展开更多
With the vigorous development of national infrastructure construction and public information construction,video surveillance systems have gradually penetrated various fields.The current key frame extraction technology...With the vigorous development of national infrastructure construction and public information construction,video surveillance systems have gradually penetrated various fields.The current key frame extraction technology has inadequate target details and inaccurate judgment of local actions.Addressing this problem,a key frame extraction method based on fractional Fourier transform is proposed.This method obtained the phase spectra information of different orders by performing fractional Fourier transform on the surveillance video frames.Next,the method designed an adaptive algorithm based on the golden section point to select the transformation order.Then,the phase spectrum information of two adjacent frames was used to characterize the changes in the global and local motion states of the target.The final step was to extract key frames based on this.Experimental results show that,compared with the previous methods,the key frames extracted by the method proposed in this paper can correctly capture the changes in the global and local motion states of the target.展开更多
Most image saliency detection models are dependent on prior knowledge and demand high computational cost. However, spectral residual（SR） and phase spectrum of the Fourier transform（PFT） models are simple and fast ...Most image saliency detection models are dependent on prior knowledge and demand high computational cost. However, spectral residual（SR） and phase spectrum of the Fourier transform（PFT） models are simple and fast saliency detection approaches based on two-dimensional Fourier transform without the prior knowledge. For seismic data, the geological structure of the underground rock formation changes more obviously in the time direction. Therefore, one-dimensional Fourier transform is more suitable for seismic saliency detection. Fractional Fourier transform（FrFT） is an improved algorithm for Fourier transform, therefore we propose the seismic SR and PFT models in one-dimensional FrF T domain to obtain more detailed saliency maps. These two models use the amplitude and phase information in FrFT domain to construct the corresponding saliency maps in spatial domain. By means of these two models, several saliency maps at different fractional orders can be obtained for seismic attribute analysis. These saliency maps can characterize the detailed features and highlight the object areas, which is more conducive to determine the location of reservoirs. The performance of the proposed method is assessed on both simulated and real seismic data. The results indicate that our method is effective and convenient for seismic attribute extraction with good noise immunity.展开更多
The classical Gerchberg-Saxton algorithm is introduced into the image recovery in fractional Fourier domain after adaptation. When this algorithm is applied directly, its performance is good for smoothed image, but ba...The classical Gerchberg-Saxton algorithm is introduced into the image recovery in fractional Fourier domain after adaptation. When this algorithm is applied directly, its performance is good for smoothed image, but bad for unsmoothed image. Based on the diversity of fractional Fourier transform on its orders, this paper suggests a novel iterative algorithm, which extracts the information of the original image from amplitudes of its fractional Fourier transform at two orders. This new algorithm consists of two independent Gerchberg-Saxton procedures and an averaging operation in each circle. Numerical simulations are carried out to show its validity for both smoothed and unsmoothed images with most pairs of orders in the interval [0, 1].展开更多
In nanoparticle sizing using the ultrafast image-based dynamic light scattering (UIDLS)method,larger impurities and dark noise from the complementary metal-oxide-semiconductor (CMOS)detector affect measurement accurac...In nanoparticle sizing using the ultrafast image-based dynamic light scattering (UIDLS)method,larger impurities and dark noise from the complementary metal-oxide-semiconductor (CMOS)detector affect measurement accuracy.To solve this problem,a two-dimensional self-adapting fast Fourier transform (2D-SAFFT)algorithm is proposed for UIDLS.Dynamic light scattering images of nanoparticles are processed using 2D fast Fourier transforms,and a high-frequency threshold and a low-frequency threshold are then set using the self-adapting algorithm to eliminate the effects of the dark noise of the CMOS detector and the impurities.The signals caused by the dark noise of the CMOS detector and the impurities are cut off using the high-frequency threshold and the low-frequency threshold.The signals without the high- and low-frequency components are then processed again using an inverse Fourier transform to obtain new images without the dark noise and impurities signals.The mean diameters of the measured nanoparticles can be obtained from images obtained using UIDLS.Five standard latex nanoparticles (46,100, 203,508,994nm)and commercial nanoparticles (antimony-doped tin oxide,indium tin oxide,TWEEN- 80,nano-Fe,and nano-Al2O3)were measured using this new method.Results show that 2D-SAFFT can effectively eliminate the effects of dark noise from the CMOS detector and the impurities.展开更多
针对以感知波形为基础的信号在通感一体化(Integrated sensing and communication,ISAC)系统中面临通信速率低、易被截获等问题,本文设计了一种基于正交相移键控(Quadrature phase shift keying,QPSK)与线性调频信号(Linear frequency m...针对以感知波形为基础的信号在通感一体化(Integrated sensing and communication,ISAC)系统中面临通信速率低、易被截获等问题,本文设计了一种基于正交相移键控(Quadrature phase shift keying,QPSK)与线性调频信号(Linear frequency modulation,LFM)的多路跳频传输架构。该架构利用多个LFM信号同时在重叠的频谱区间传输以提高符号速率,并通过LFM子载波的跳频特性实现加密通信。此外,通过结合动态前导码与数据的时分复用机制,该方案有效地提升了多路LFM信号的路径索引和参数估计精度。针对符号解调,本文提出两种基于非相干离散啁啾傅里叶变换(Noncoherent discrete chirp Fourier transform,NC⁃DCFT)的多峰值检测算法。仿真结果表明,在相同符号速率约束下,本文所提出的多路并行架构在误码率方面优于传统单路方案,当信噪比为0 dB时,4路并行架构的误码率相较于单路方案降低了一个数量级。同时,动态前导码方案满足不同场景下的路径索引识别需求,在信噪比为0 dB时,归一化均方差均低于10-2。此外,面向功率均衡、功率差异显著及载波参数保护间隔较小3种复杂场景设计的符号检测算法,在其适配场景下均可实现误码率低于10-2。最后,跳频机制显著增强了系统的抗截获能力,即使50%参数泄露,第3方对信号的恢复概率(Probability of accurate recovery,PAR)仍被压制在7%以下,验证了该方案的鲁棒性与应用价值。展开更多
针对全相位频谱分析算法对采样序列中心样点有特殊要求以及当频偏量绝对值为0.5时会影响频率估计值的问题,提出了一种改进的全相位时移相位差频谱分析算法。该算法首先对序列向左循环移动一位,形成只有一位时移关系的两个序列,然后分别...针对全相位频谱分析算法对采样序列中心样点有特殊要求以及当频偏量绝对值为0.5时会影响频率估计值的问题,提出了一种改进的全相位时移相位差频谱分析算法。该算法首先对序列向左循环移动一位,形成只有一位时移关系的两个序列,然后分别进行全相位快速傅里叶变换(all phase fast Fourier transform,APFFT),计算过程中忽略相位差补偿值,避免频偏量的引入,通过两序列主谱线间相位差的直接计算便可得到信号的频率和初相估计值。仿真实验表明该算法计算简单,适用范围广,参数估计精度高且频率估计精度稳定性好。展开更多
文摘The quaternion Fourier transform plays a vital role in the representation of two-dimensional signals. This paper characterizes spectrum of quaternion-valued signals on the quaternion Fourier transform domain by the partial derivative.
基金spported by he key-area andevelopment programof Guangdongprovince(Grant No.2019B01013700)National Nature Science Foundation of China(Grant No.61702347)+2 种基金Natural Science Foundation of Hebei Province(Grant No.F2017210161)Science andTechnology Research Project of Higher Education in Hebei Province(Grant No.QN2017132)Graduate Innovation Program(Grant No.YC2022051).
文摘With the improvement of people’s security awareness,numerous monitoring equipment has been put into use,resulting in the explosive growth of surveillance video data.Key frame extraction technology is a paramount technology for improving video storage efficiency and enhancing the accuracy of video retrieval.It can extract key frame sets that can express video content from massive videos.However,the existing key frame extraction algorithms of surveillance video still have deficiencies,such as the destruction of image information integrity and the inability to extract key frames accurately.To this end,this paper proposes a key frame extraction algorithm of surveillance video based on quaternion Fourier saliency detection.Firstly,the algorithm used colors,and intensity features to perform quaternion Fourier transform on surveillance video sequences.Next,the phase spectrum of the quaternion Fourier transformed image was obtained,and he image visual saliency map was obtained according to the quaternion Fourier phase spectrum.Then,the image visual saliency map of two adjacent frames is used to characterize the change of target motion state.Finally,the frames that can accurately express the motion state of the target are selected as key frames.The experimental results show that the method proposed in this paper can accurately capture the changes of the local motion state of the target while maintaining the integrity of the image information.
基金supported by the National Natural Science Foundation of China(Nos.61702347,62027801 and 61972267)Natural Science Fund of Hebei Province(No.F2017210161),and Hebei Province Graduate Student Innovation Ability Training Funding Project.
文摘With the vigorous development of national infrastructure construction and public information construction,video surveillance systems have gradually penetrated various fields.The current key frame extraction technology has inadequate target details and inaccurate judgment of local actions.Addressing this problem,a key frame extraction method based on fractional Fourier transform is proposed.This method obtained the phase spectra information of different orders by performing fractional Fourier transform on the surveillance video frames.Next,the method designed an adaptive algorithm based on the golden section point to select the transformation order.Then,the phase spectrum information of two adjacent frames was used to characterize the changes in the global and local motion states of the target.The final step was to extract key frames based on this.Experimental results show that,compared with the previous methods,the key frames extracted by the method proposed in this paper can correctly capture the changes in the global and local motion states of the target.
基金supported by the National Natural Science Foundation of China (Nos.61571096,61775030,41274127,41301460,and 40874066)
文摘Most image saliency detection models are dependent on prior knowledge and demand high computational cost. However, spectral residual（SR） and phase spectrum of the Fourier transform（PFT） models are simple and fast saliency detection approaches based on two-dimensional Fourier transform without the prior knowledge. For seismic data, the geological structure of the underground rock formation changes more obviously in the time direction. Therefore, one-dimensional Fourier transform is more suitable for seismic saliency detection. Fractional Fourier transform（FrFT） is an improved algorithm for Fourier transform, therefore we propose the seismic SR and PFT models in one-dimensional FrF T domain to obtain more detailed saliency maps. These two models use the amplitude and phase information in FrFT domain to construct the corresponding saliency maps in spatial domain. By means of these two models, several saliency maps at different fractional orders can be obtained for seismic attribute analysis. These saliency maps can characterize the detailed features and highlight the object areas, which is more conducive to determine the location of reservoirs. The performance of the proposed method is assessed on both simulated and real seismic data. The results indicate that our method is effective and convenient for seismic attribute extraction with good noise immunity.
文摘The classical Gerchberg-Saxton algorithm is introduced into the image recovery in fractional Fourier domain after adaptation. When this algorithm is applied directly, its performance is good for smoothed image, but bad for unsmoothed image. Based on the diversity of fractional Fourier transform on its orders, this paper suggests a novel iterative algorithm, which extracts the information of the original image from amplitudes of its fractional Fourier transform at two orders. This new algorithm consists of two independent Gerchberg-Saxton procedures and an averaging operation in each circle. Numerical simulations are carried out to show its validity for both smoothed and unsmoothed images with most pairs of orders in the interval [0, 1].
基金National Natural Science Foundation of China (Grant No.51573093).
文摘In nanoparticle sizing using the ultrafast image-based dynamic light scattering (UIDLS)method,larger impurities and dark noise from the complementary metal-oxide-semiconductor (CMOS)detector affect measurement accuracy.To solve this problem,a two-dimensional self-adapting fast Fourier transform (2D-SAFFT)algorithm is proposed for UIDLS.Dynamic light scattering images of nanoparticles are processed using 2D fast Fourier transforms,and a high-frequency threshold and a low-frequency threshold are then set using the self-adapting algorithm to eliminate the effects of the dark noise of the CMOS detector and the impurities.The signals caused by the dark noise of the CMOS detector and the impurities are cut off using the high-frequency threshold and the low-frequency threshold.The signals without the high- and low-frequency components are then processed again using an inverse Fourier transform to obtain new images without the dark noise and impurities signals.The mean diameters of the measured nanoparticles can be obtained from images obtained using UIDLS.Five standard latex nanoparticles (46,100, 203,508,994nm)and commercial nanoparticles (antimony-doped tin oxide,indium tin oxide,TWEEN- 80,nano-Fe,and nano-Al2O3)were measured using this new method.Results show that 2D-SAFFT can effectively eliminate the effects of dark noise from the CMOS detector and the impurities.
文摘针对以感知波形为基础的信号在通感一体化(Integrated sensing and communication,ISAC)系统中面临通信速率低、易被截获等问题,本文设计了一种基于正交相移键控(Quadrature phase shift keying,QPSK)与线性调频信号(Linear frequency modulation,LFM)的多路跳频传输架构。该架构利用多个LFM信号同时在重叠的频谱区间传输以提高符号速率,并通过LFM子载波的跳频特性实现加密通信。此外,通过结合动态前导码与数据的时分复用机制,该方案有效地提升了多路LFM信号的路径索引和参数估计精度。针对符号解调,本文提出两种基于非相干离散啁啾傅里叶变换(Noncoherent discrete chirp Fourier transform,NC⁃DCFT)的多峰值检测算法。仿真结果表明,在相同符号速率约束下,本文所提出的多路并行架构在误码率方面优于传统单路方案,当信噪比为0 dB时,4路并行架构的误码率相较于单路方案降低了一个数量级。同时,动态前导码方案满足不同场景下的路径索引识别需求,在信噪比为0 dB时,归一化均方差均低于10-2。此外,面向功率均衡、功率差异显著及载波参数保护间隔较小3种复杂场景设计的符号检测算法,在其适配场景下均可实现误码率低于10-2。最后,跳频机制显著增强了系统的抗截获能力,即使50%参数泄露,第3方对信号的恢复概率(Probability of accurate recovery,PAR)仍被压制在7%以下,验证了该方案的鲁棒性与应用价值。
文摘针对全相位频谱分析算法对采样序列中心样点有特殊要求以及当频偏量绝对值为0.5时会影响频率估计值的问题,提出了一种改进的全相位时移相位差频谱分析算法。该算法首先对序列向左循环移动一位,形成只有一位时移关系的两个序列,然后分别进行全相位快速傅里叶变换(all phase fast Fourier transform,APFFT),计算过程中忽略相位差补偿值,避免频偏量的引入,通过两序列主谱线间相位差的直接计算便可得到信号的频率和初相估计值。仿真实验表明该算法计算简单,适用范围广,参数估计精度高且频率估计精度稳定性好。
