Frame rate is an important metric for ultrasound imaging systems,and high frame rates(HFR)benefit moving-target imaging.One common way to obtain HFR imaging is to transmit a plane wave.Delay-and-sum(DAS)beamformer is ...Frame rate is an important metric for ultrasound imaging systems,and high frame rates(HFR)benefit moving-target imaging.One common way to obtain HFR imaging is to transmit a plane wave.Delay-and-sum(DAS)beamformer is a conventional beamforming algorithm,which is simple and has been widely implemented in clinical application.Fourier beamforming is an alternative method for HFR imaging and has high levels of imaging efficiency,imaging speed,and good temporal dynamic characteristics.Nevertheless,the resolution and contrast performance of HFR imaging based on DAS or Fourier beamforming are insufficient due to the single plane wave transmission.To address this problem,a joint DAS and Fourier beamforming method is introduced in this study.The proposed method considers the different distributions of sidelobes in DAS imaging and Fourier imaging and combines the angular spectrum and DAS to reconstruct ultrasound images.The proposed method is evaluated on simulation and experimental phantom datasets to compare its performance with DAS and Fourier beamforming methods.Results demonstrate that the proposed method improves image effective dynamic range and resolution while also retaining a high frame rate of the ultrasound imaging systems.The proposed method improves the effective dynamic range along axial and lateral directions by 10 dB,compared to standard DAS and Fourier beamforming.展开更多
The high frame rate(HFR)imaging technique requires only one emission event for imaging.Therefore,it can achieve ultrafast imaging with frame rates up to the kHz regime,which satisfies the frame rate requirements for i...The high frame rate(HFR)imaging technique requires only one emission event for imaging.Therefore,it can achieve ultrafast imaging with frame rates up to the kHz regime,which satisfies the frame rate requirements for imaging moving tissues in scientific research and clinics.Lu’s Fourier migration method is based on a non-diffraction beam to obtain HFR images and can improve computational speed and efficiency.However,in order to obtain high-quality images,Fourier migration needs to make full use of the spectrum of echo signals for imaging,which requires a large number of Fast Fourier Transform(FFT)points and increases the complexity of the hardware when the echo frequency is high.Here,an efficient algorithm using the spectrum migration technique based on the spectrum’s distribution characteristics is proposed to improve the imaging efficiency in HFR imaging.Since the actual echo signal spectrum is of limited bandwidth,low-frequency and high-frequency parts with low-energy have little contribution to the imaging spectrum.We transform the effective part that provides the main energy in the signal spectrum to the imaging spectrum while the ineffective spectrum components are not utilized for imaging.This can significantly reduce the number of Fourier transform points,improve Fourier imaging efficiency,and ensure the imaging quality.The proposed method is evaluated on simulated and experimental datasets.Results demonstrated that the proposed method could achieve equivalent image quality with a reduced point number for FFT compared to the complete spectrum migration.In this paper,it only requires a quarter of the FFT points used in the complete spectrum migration,which can improve the computational efficiency;thus,it is more suitable for real-time data processing.The proposed spectrum migration method has a specific significance for the study and clinical application of HFR imaging.展开更多
Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were d...Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were derived. We performed the study of 3D pulse echo imaging with limited diffraction array beam. To obtain high frame rate images, a single plane wave pulse (broadband) was transmitted with the arrays. Echoes received with the same arrays were processed with Fourier method to construct 3D images. Results Compared with traditional pulse echo imaging, this method has a larger depth of field, high frame rate, and high signal to noise ratio. Conclusion The new method has prospect of high frame rate 3D imaging. In addition, the imaging system based this method is easily implemented and has high quality image.展开更多
In this paper, multiresolution critical-point filters （CPFs） are employed to image matching for frame rate up-conversion （FRUC）. By CPF matching, the dense motion field can be obtained for representing object moti...In this paper, multiresolution critical-point filters （CPFs） are employed to image matching for frame rate up-conversion （FRUC）. By CPF matching, the dense motion field can be obtained for representing object motions accurately. However, the elastic motion model does not hold in the areas of occlusion, thus resulting in blur artifacts in the interpolated frame. To tackle this problem, we propose a new FRUC scheme using an occlusion refined CPF matching interpolation （ORCMI）. In the proposed approach, the occlusion refinement is based on a bidirectional CPF mapping. And the intermediate frames are generated by the bidirectional interpolation for non-occlusion pixels combined with unidirectional projection for the occlusion pixels. Ex- perimental results show that ORCMI improves the visual quality of the interpolated frames, especially at the occlusion regions. Compared to the block matching based FRUC algorithm, ORCM1 can achieve 1-2 dB PSNR gain for standard video sequences.展开更多
The goal of this paper is to improve human visual perceptual quality as well as coding efficiency of H. 264 video at low bit rate conditions by adaptively adjusting the number of skipped frames. The encoding frames ar...The goal of this paper is to improve human visual perceptual quality as well as coding efficiency of H. 264 video at low bit rate conditions by adaptively adjusting the number of skipped frames. The encoding frames are selected according to the motion activity of each frame and the motion accumulation of successive frames. The motion activity analysis is based on the statistics of motion vectors and with consider- ation of the characteristics of H. 264 coding standard. A prediction model of motion accumulation is pro- posed to reduce complex computation of motion estimation. The dynamic encoding frame rate control algorithm is applied to both the frame level and the GOB （Group of Macroblocks ） level. Simulation is done to compare the performance of JM76 with the proposed frame level scheme and GOB level scheme.展开更多
Background Coronary artery disease(CAD)is a leading cause of mortality worldwide.Percutaneous coronary intervention(PCI)is a standard treatment for CAD,yet the radiation exposure associated with this procedure can pos...Background Coronary artery disease(CAD)is a leading cause of mortality worldwide.Percutaneous coronary intervention(PCI)is a standard treatment for CAD,yet the radiation exposure associated with this procedure can pose significant risks to both patients and healthcare professionals.With the aim to optimize this procedure,we studied the effects of different exposure rates on radiation dose,fluoroscopy time,and procedural complications.Methods A total of 441 consecutive patients who underwent coronary angiography and subsequent PCI treatment from January 2020 to December 2021 were included in this study.Baseon the fluoroscopy frame rates used during the procedure,patients were divided into two groups,which included a standard dose protocol(SDP)group that used15 frames per second(FPS)and a low dose protocol(LDP)group that used 7.5 FPS.Then the impact of different fluoroscopy frame rates on total air kerma(AK),procedure time,fluoroscopy times(FT),and procedural complications in patients undergoing PCI were evaluated.Results Our data indicated that LDP group had a significantly lower AK,indicative of a reduced radiation dose,in comparison to SDP group.Although the procedure time and FT were slightly longer in the LDP group,this increase was not statistically significant.Moreover,the rate of intraoperative complications in the LDP group was not higher than that in the SDP group.In a subgroup of patients who underwent intravascular ultrasound(IVUS)within the LDP group,we observed further reductions in radiation exposure and FT.Conclusions The use of reduced fluoroscopy frame rates and adjunctive IVUS during PCI procedures can be a viable approach to minimizing radiation exposure without compromising procedure success or patient safety.展开更多
Intra-frame plays a significant role in improving video quality for rate control of H.264/AVC.In this paper,an efficient intra-frame rate control algorithm is proposed for H.264/AVC video coding.The proposed scheme ad...Intra-frame plays a significant role in improving video quality for rate control of H.264/AVC.In this paper,an efficient intra-frame rate control algorithm is proposed for H.264/AVC video coding.The proposed scheme adjusts the quantization parameter （QP） of intra-frame adaptively according to intra-frame buffer fullness ratio,current buffer fullness ratio,and skipped frame ratio.Experimental results demonstrate that for a set of typical testing sequences,the proposed scheme can obtain accurate target bit rate,better peak signal-to-noise ratio （PSNR） performance and reduce the number of skipped frames significantly,when compared with existing schemes.More importantly,the proposed scheme is very flexible for different initial QPs and target bits.展开更多
The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave...The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.展开更多
Background and Aims:This study aimed to evaluate the diagnostic performance of high frame rate contrast-en-hanced ultrasound(H-CEUS)of focal liver lesions(FLLs).Methods:From July 2017 to June 2019,conventional con-tra...Background and Aims:This study aimed to evaluate the diagnostic performance of high frame rate contrast-en-hanced ultrasound(H-CEUS)of focal liver lesions(FLLs).Methods:From July 2017 to June 2019,conventional con-trast-enhanced ultrasound(C-CEUS)and H-CEUS were per-formed in 78 patients with 78 nodules.The characteristics of C-CEUS and H-CEUS in malignant and benign groups and the differences between different lesion sizes(1-3 cm,3-5 cm,or>5 cm)of C-CEUS and H-CEUS were examined.The diagnostic performance of C-CEUS and H-CEUS was ana-lyzed.The chi-square test or Fisher’s exact test was used to assess inter-group differences.The receiver operating characteristic curve was plotted to determine the diagnostic performance of C-CEUS and H-CEUS.Results:There were significant differences in the enhancement area,fill-in direc-tion and vascular architecture between C-CEUS and H-CEUS for both benign and malignant lesions(all p=0.000-0.008),but there were no significant differences in washout results(p=0.566 and p=0.684,respectively).For lesions 1-3 cm in size,the enhancement area,fill-in direction,and vascular architecture on C-CEUS and H-CEUS were significantly dif-ferent(all p=0.000),unlike for lesions 3-5 cm or>5 cm in size.For differentiation of malignant from benign FLLs in the 1-3 cm group,H-CEUS showed sensitivity,specific-ity,accuracy,and positive and negative predictive values of 92.86%,95.0%,96.3%,90.48%and 93.75%,respectively,which were higher than those for C-CEUS(75.0%,70.0%,77.78%,66.67%and 72.91%,respectively).Conclusions:H-CEUS provided more vascular information which could help differentiate malignant from benign FLLs,especially for lesions 1-3 cm in size.展开更多
Interactive holography offers unmatched levels of immersion and user engagement in the field of future display.Despite of the substantial progress has been made in dynamic meta-holography,the realization of real-time,...Interactive holography offers unmatched levels of immersion and user engagement in the field of future display.Despite of the substantial progress has been made in dynamic meta-holography,the realization of real-time,highly smooth interactive holography remains a significant challenge due to the computational and display frame rate limitations.In this study,we introduced a dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates.To our knowledge,this is the first reported practical dynamic interactive metasurface holographic system.We spa-tially divided the metasurface device into multiple distinct channels,each projecting a reconstructed sub-pattern.The switching states of these channels were mapped to bitwise operations on a set of bit values,which avoids complex holo-gram computations,enabling an ultra-high computational frame rate.Our approach achieves a computational frame rate of 800 kHz and a display frame rate of 23 kHz on a low-power Raspberry Pi computational platform.According to this methodology,we demonstrated an interactive dynamic holographic Tetris game system that allows interactive gameplay,color display,and on-the-fly hologram creation.Our technology presents an inspiration for advanced dynamic meta-holography,which is promising for a broad range of applications including advanced human-computer interaction,real-time 3D visualization,and next-generation virtual and augmented reality systems.展开更多
A very high frame rate camera is designed based on an innovative CCD driving method. The CCD driving method is mainly implemented on frame transfer CCDs. Asynchronous drive timing sequences are applied in the image an...A very high frame rate camera is designed based on an innovative CCD driving method. The CCD driving method is mainly implemented on frame transfer CCDs. Asynchronous drive timing sequences are applied in the image and storage section of the CCDs. Several rows of the charge in the image section are binned onto the same row in the storage section, and there are the same number of images to be stored in the storage section before they are read out. Based on the new driving method, the frame transfer CCDs can work at a very high frame rate in acquiring burst images though the reading speed remains at a lower level. A very high frame rate camera is designed in this paper. The innovative CCD driving method is mainly of concern. An e2v’s CCD60 is adopted in the camera system, whose full size resolution is 128×128, and the up most frame rate is 1000 Hz in the conventional CCD driving method. By using the presented method, the CCD60 based imager is capable of operating at up to 40000 frames per second （fps） at a recognizable resolution of 128×32. Comparing cameras using traditional binning and region of interest technologies, the frame rate is normally less than 5000 fps while the resolution is only 32×32 left.展开更多
BACKGROUND Liver metastasis of duodenal gastrointestinal stromal tumor(GIST)is rare.Most reports mainly focus on its treatment and approaches to surgical resection,while details on its contrast-enhanced ultrasound(CEU...BACKGROUND Liver metastasis of duodenal gastrointestinal stromal tumor(GIST)is rare.Most reports mainly focus on its treatment and approaches to surgical resection,while details on its contrast-enhanced ultrasound(CEUS)findings are lacking.The diagnosis and imaging modalities for this condition remain challenging.CASE SUMMARY A 53-year-old Chinese man presented with mild signs and symptoms of the digestive tract.He underwent routine examinations after GIST surgery.Magnetic resonance imaging showed a 2.3 cm hepatic space-occupying lesion.All the laboratory test results were within normal limits.For further diagnostic confirmation,we conducted high frame rate CEUS(H-CEUS)and found a malignant perfusion pattern.Heterogeneous concentric hyper-enhancement,earlier wash-in than the liver parenchyma,and two irregular vessel columns could be observed at the periphery of the lesion during the arterial phase.Ultrasound-guided puncture biopsy was used to confirm the diagnosis of the lesion as liver metastasis of duodenal GIST.Imatinib was prescribed after biopsy,and the patient’s clinical course was monitored.CONCLUSION H-CEUS is useful for detecting microcirculation differences,wash-in patterns,and vascular morphogenesis and diagnosing liver metastasis of duodenal GIST.展开更多
The orbital angular momentum(OAM)of light has been implemented as an information carrier in OAM holography.Holographic information can be multiplexed in theoretical unbounded OAM channels,promoting the applications of...The orbital angular momentum(OAM)of light has been implemented as an information carrier in OAM holography.Holographic information can be multiplexed in theoretical unbounded OAM channels,promoting the applications of optically addressable dynamic display and high-security optical encryption.However,the frame-rate of the dynamic extraction of the information reconstruction process in OAM holography is physically determined by the switching speed of the incident OAM states,which is currently below 30 Hz limited by refreshing rate of the phase-modulation spatial light modulator(SLM).Here,based on a cross convolution with the spatial frequency of the OAM-multiplexing hologram,the spatial frequencies of an elaborately-designed amplitude distribution,namely amplitude decoding key,has been adopted for the extraction of three-dimensional holographic information encoded in a specific OAM information channel.We experimentally demonstrated a dynamic extraction frame rate of 100 Hz from an OAM multiplexing hologram with 10 information channels indicated by individual OAM values from-50 to 50.The new concept of cross convolution theorem can even provide the potential of parallel reproduction and distribution of information encoded in many OAM channels at various positions which boosts the capacity of information processing far beyond the traditional decoding methods.Thus,our results provide a holographic paradigm for high-speed 3D information processing,paving an unprecedented way to achieve the high-capacity short-range optical communication system.展开更多
Frame rate is corresponding to the temporal resolution and the number of the pixels of the picture is corresponding to the spatial resolution. They are both very important for the researchers. The ideal image analysis...Frame rate is corresponding to the temporal resolution and the number of the pixels of the picture is corresponding to the spatial resolution. They are both very important for the researchers. The ideal image analysis and processing system should have high spatiotemporal characteristics, which is much expensive in practical use. A new method to enhance dynamic frame rate using multi-digital camera(DC) is proposed and the result shows that it could increase the frame rate effectively and decreases the cost in practical use.展开更多
We propose a Rate-Distortion (RD) optimized strategy for frame-dropping and scheduling of multi-user conversa- tional and streaming videos. We consider a scenario where conversational and streaming videos share the fo...We propose a Rate-Distortion (RD) optimized strategy for frame-dropping and scheduling of multi-user conversa- tional and streaming videos. We consider a scenario where conversational and streaming videos share the forwarding resources at a network node. Two buffers are setup on the node to temporarily store the packets for these two types of video applications. For streaming video, a big buffer is used as the associated delay constraint of the application is moderate and a very small buffer is used for conversational video to ensure that the forwarding delay of every packet is limited. A scheduler is located behind these two buffers that dynamically assigns transmission slots on the outgoing link to the two buffers. Rate-distortion side information is used to perform RD-optimized frame dropping in case of node overload. Sharing the data rate on the outgoing link between the con- versational and the streaming videos is done either based on the fullness of the two associated buffers or on the mean incoming rates of the respective videos. Simulation results showed that our proposed RD-optimized frame dropping and scheduling ap- proach provides significant improvements in performance over the popular priority-based random dropping (PRD) technique.展开更多
Most of the traditional methods are based on block motion compensation tending to involve heavy blocking artifacts in the interpolated frames. In this paper, a new frame interpolation method with pixel-level motion ve...Most of the traditional methods are based on block motion compensation tending to involve heavy blocking artifacts in the interpolated frames. In this paper, a new frame interpolation method with pixel-level motion vector field （MVF） is proposed. Our method consists of the following four steps： （i） applying the pixel-level motion vectors （MVs） estimated by optical flow algorithm to eliminate blocking artifacts （ii） motion post-processing and super-sampling anti-aliasing to solve the problems caused by pixel-level MVs （iii） robust warping method to address collisions and holes caused by occlusions （iv） a new holes filling method using triangular mesh （HFTM） to reduce the artifacts caused by holes. Experimental results show that the proposed method can effectively alleviate the holes and blocking artifacts in interpolated frames, and outperforms existing methods both in terms of objective and subjective performances, especially for sequences with complex motions.展开更多
A dynamic learning rate Gaussian mixture model（GMM）algorithm is proposed to deal with the problem of slow adaption of GMM in the case of moving object detection in the outdoor surveillance,especially in the presence...A dynamic learning rate Gaussian mixture model（GMM）algorithm is proposed to deal with the problem of slow adaption of GMM in the case of moving object detection in the outdoor surveillance,especially in the presence of sudden illumination changes.The GMM is mostly used for detecting objects in complex scenes for intelligent monitoring systems.To solve this problem,a mixture Gaussian model has been built for each pixel in the video frame,and according to the scene change from the frame difference,the learning rate of GMM can be dynamically adjusted.The experiments show that the proposed method gives good results with an adaptive GMM learning rate when we compare it with GMM method with a fixed learning rate.The method was tested on a certain dataset,and tests in the case of sudden natural light changes show that our method has a better accuracy and lower false alarm rate.展开更多
Efficient anti-jamming rateless coding based on cognitive Orthogonal Frequency Division Multiplexing (OFDM) modulation in Cognitive Radio Network (CRN) is mainly discussed. Rateless coding with small redundancy and lo...Efficient anti-jamming rateless coding based on cognitive Orthogonal Frequency Division Multiplexing (OFDM) modulation in Cognitive Radio Network (CRN) is mainly discussed. Rateless coding with small redundancy and low complexity is presented, and the optimal design methods of building rateless codes are also proposed. In CRN, anti-jamming rateless coding could recover the lost packets in parallel channels of cognitive OFDM, thus it protects Secondary Users (SUs) from the in-terference by Primary Users (PUs) efficiently. Frame Error Rate (FER) and throughput performance of SU employing anti-jamming rateless coding are analyzed in detail. Performance comparison between rateless coding and piecewise coding are also presented. It is shown that, anti-jamming rateless coding provides low FER and Word Error Rate (WER) performance with uniform sub-channel selection. Meanwhile, it is also verified that, in higher jamming rate and longer code redundancy scenario, rateless coding method could achieve better FER and throughput performance than another anti-jamming coding schemes.展开更多
Frame processing method offers a model-based approach to Inverse Synthetic Aperture Radar(ISAR) imaging. It also provides a way to estimate the rotation rate of a non-cooperative target from radar returns via the fram...Frame processing method offers a model-based approach to Inverse Synthetic Aperture Radar(ISAR) imaging. It also provides a way to estimate the rotation rate of a non-cooperative target from radar returns via the frame operator properties. In this paper, the relationship between the best achievable ISAR image and the reconstructed image from radar returns was derived in the framework of Finite Frame Processing theory. We show that image defocusing caused by the use of an incorrect target rotation rate is interpreted under the FP method as a frame operator mismatch problem which causes energy dispersion. The unknown target rotation rate may be computed by optimizing the frame operator via a prominent point. Consequently, a prominent intensity maximization method in FP framework was proposed to estimate the underlying target rotation rate from radar returns. In addition, an image filtering technique was implemented to assist searching for a prominent point in practice. The proposed method is justified via a simulation analysis on the performance of FP imaging versus target rotation rate error.Effectiveness of the proposed method is also confirmed from real ISAR data experiments.展开更多
The pilotless frame synchronization approach and implementations of LDPC code are the crucial issue of LDPC decoder. The Maximum-A-Posteriori probability( MAP) decoder has a perfect frame synchronization error rate( F...The pilotless frame synchronization approach and implementations of LDPC code are the crucial issue of LDPC decoder. The Maximum-A-Posteriori probability( MAP) decoder has a perfect frame synchronization error rate( FSER) performance. In this paper,a theoretical derivation of the FSER performance of pilotless frame synchronization for LDPC code is presented. The FSER performance by theoretical analysis coincides well with that by simulation in additive white Gaussian channel and Rician fading channel. So it is estimated the FSER performance of an LDPC code by theoretical analysis can be used instead of the simulations which are much more time-consuming.展开更多
基金supported by National Natural Science Foundation of China(Project Nos.61201060 and 61172037)supported by National Natural Science Foundation of China,http://www.nsfc.gov.cn/.Peng H.received the project No.61172037 and Zheng C.received the project No.61201060.
文摘Frame rate is an important metric for ultrasound imaging systems,and high frame rates(HFR)benefit moving-target imaging.One common way to obtain HFR imaging is to transmit a plane wave.Delay-and-sum(DAS)beamformer is a conventional beamforming algorithm,which is simple and has been widely implemented in clinical application.Fourier beamforming is an alternative method for HFR imaging and has high levels of imaging efficiency,imaging speed,and good temporal dynamic characteristics.Nevertheless,the resolution and contrast performance of HFR imaging based on DAS or Fourier beamforming are insufficient due to the single plane wave transmission.To address this problem,a joint DAS and Fourier beamforming method is introduced in this study.The proposed method considers the different distributions of sidelobes in DAS imaging and Fourier imaging and combines the angular spectrum and DAS to reconstruct ultrasound images.The proposed method is evaluated on simulation and experimental phantom datasets to compare its performance with DAS and Fourier beamforming methods.Results demonstrate that the proposed method improves image effective dynamic range and resolution while also retaining a high frame rate of the ultrasound imaging systems.The proposed method improves the effective dynamic range along axial and lateral directions by 10 dB,compared to standard DAS and Fourier beamforming.
基金supported by National Natural Science Foundation of China,http://www.nsfc.gov.cn/.Peng H.received the project No.62071165.
文摘The high frame rate(HFR)imaging technique requires only one emission event for imaging.Therefore,it can achieve ultrafast imaging with frame rates up to the kHz regime,which satisfies the frame rate requirements for imaging moving tissues in scientific research and clinics.Lu’s Fourier migration method is based on a non-diffraction beam to obtain HFR images and can improve computational speed and efficiency.However,in order to obtain high-quality images,Fourier migration needs to make full use of the spectrum of echo signals for imaging,which requires a large number of Fast Fourier Transform(FFT)points and increases the complexity of the hardware when the echo frequency is high.Here,an efficient algorithm using the spectrum migration technique based on the spectrum’s distribution characteristics is proposed to improve the imaging efficiency in HFR imaging.Since the actual echo signal spectrum is of limited bandwidth,low-frequency and high-frequency parts with low-energy have little contribution to the imaging spectrum.We transform the effective part that provides the main energy in the signal spectrum to the imaging spectrum while the ineffective spectrum components are not utilized for imaging.This can significantly reduce the number of Fourier transform points,improve Fourier imaging efficiency,and ensure the imaging quality.The proposed method is evaluated on simulated and experimental datasets.Results demonstrated that the proposed method could achieve equivalent image quality with a reduced point number for FFT compared to the complete spectrum migration.In this paper,it only requires a quarter of the FFT points used in the complete spectrum migration,which can improve the computational efficiency;thus,it is more suitable for real-time data processing.The proposed spectrum migration method has a specific significance for the study and clinical application of HFR imaging.
文摘Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were derived. We performed the study of 3D pulse echo imaging with limited diffraction array beam. To obtain high frame rate images, a single plane wave pulse (broadband) was transmitted with the arrays. Echoes received with the same arrays were processed with Fourier method to construct 3D images. Results Compared with traditional pulse echo imaging, this method has a larger depth of field, high frame rate, and high signal to noise ratio. Conclusion The new method has prospect of high frame rate 3D imaging. In addition, the imaging system based this method is easily implemented and has high quality image.
基金Project (No. 2004C21052) supported by the Key Program of the Science and Technology Commission Foundation of Zhejiang Province, China
文摘In this paper, multiresolution critical-point filters （CPFs） are employed to image matching for frame rate up-conversion （FRUC）. By CPF matching, the dense motion field can be obtained for representing object motions accurately. However, the elastic motion model does not hold in the areas of occlusion, thus resulting in blur artifacts in the interpolated frame. To tackle this problem, we propose a new FRUC scheme using an occlusion refined CPF matching interpolation （ORCMI）. In the proposed approach, the occlusion refinement is based on a bidirectional CPF mapping. And the intermediate frames are generated by the bidirectional interpolation for non-occlusion pixels combined with unidirectional projection for the occlusion pixels. Ex- perimental results show that ORCMI improves the visual quality of the interpolated frames, especially at the occlusion regions. Compared to the block matching based FRUC algorithm, ORCM1 can achieve 1-2 dB PSNR gain for standard video sequences.
基金Supported by the High Technology. Research and Development Program of China （No. 2005AA103310） and the National Natural Science Foundation of China （No. 60202006）.
文摘The goal of this paper is to improve human visual perceptual quality as well as coding efficiency of H. 264 video at low bit rate conditions by adaptively adjusting the number of skipped frames. The encoding frames are selected according to the motion activity of each frame and the motion accumulation of successive frames. The motion activity analysis is based on the statistics of motion vectors and with consider- ation of the characteristics of H. 264 coding standard. A prediction model of motion accumulation is pro- posed to reduce complex computation of motion estimation. The dynamic encoding frame rate control algorithm is applied to both the frame level and the GOB （Group of Macroblocks ） level. Simulation is done to compare the performance of JM76 with the proposed frame level scheme and GOB level scheme.
基金supported by the open subject project of the State Key Laboratory of Causes and Prevention of Central Asian High Morbidity and Prevention jointly established by the province and the Ministry(No.SKL-HIDCA-2020-KS8)。
文摘Background Coronary artery disease(CAD)is a leading cause of mortality worldwide.Percutaneous coronary intervention(PCI)is a standard treatment for CAD,yet the radiation exposure associated with this procedure can pose significant risks to both patients and healthcare professionals.With the aim to optimize this procedure,we studied the effects of different exposure rates on radiation dose,fluoroscopy time,and procedural complications.Methods A total of 441 consecutive patients who underwent coronary angiography and subsequent PCI treatment from January 2020 to December 2021 were included in this study.Baseon the fluoroscopy frame rates used during the procedure,patients were divided into two groups,which included a standard dose protocol(SDP)group that used15 frames per second(FPS)and a low dose protocol(LDP)group that used 7.5 FPS.Then the impact of different fluoroscopy frame rates on total air kerma(AK),procedure time,fluoroscopy times(FT),and procedural complications in patients undergoing PCI were evaluated.Results Our data indicated that LDP group had a significantly lower AK,indicative of a reduced radiation dose,in comparison to SDP group.Although the procedure time and FT were slightly longer in the LDP group,this increase was not statistically significant.Moreover,the rate of intraoperative complications in the LDP group was not higher than that in the SDP group.In a subgroup of patients who underwent intravascular ultrasound(IVUS)within the LDP group,we observed further reductions in radiation exposure and FT.Conclusions The use of reduced fluoroscopy frame rates and adjunctive IVUS during PCI procedures can be a viable approach to minimizing radiation exposure without compromising procedure success or patient safety.
基金Supported by the National Science Foundation for Creative Research Groups of China (60821062)
文摘Intra-frame plays a significant role in improving video quality for rate control of H.264/AVC.In this paper,an efficient intra-frame rate control algorithm is proposed for H.264/AVC video coding.The proposed scheme adjusts the quantization parameter （QP） of intra-frame adaptively according to intra-frame buffer fullness ratio,current buffer fullness ratio,and skipped frame ratio.Experimental results demonstrate that for a set of typical testing sequences,the proposed scheme can obtain accurate target bit rate,better peak signal-to-noise ratio （PSNR） performance and reduce the number of skipped frames significantly,when compared with existing schemes.More importantly,the proposed scheme is very flexible for different initial QPs and target bits.
基金Supported by the Short-wave Infrared Camera Systems(B025F40622024)。
文摘The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.
文摘Background and Aims:This study aimed to evaluate the diagnostic performance of high frame rate contrast-en-hanced ultrasound(H-CEUS)of focal liver lesions(FLLs).Methods:From July 2017 to June 2019,conventional con-trast-enhanced ultrasound(C-CEUS)and H-CEUS were per-formed in 78 patients with 78 nodules.The characteristics of C-CEUS and H-CEUS in malignant and benign groups and the differences between different lesion sizes(1-3 cm,3-5 cm,or>5 cm)of C-CEUS and H-CEUS were examined.The diagnostic performance of C-CEUS and H-CEUS was ana-lyzed.The chi-square test or Fisher’s exact test was used to assess inter-group differences.The receiver operating characteristic curve was plotted to determine the diagnostic performance of C-CEUS and H-CEUS.Results:There were significant differences in the enhancement area,fill-in direc-tion and vascular architecture between C-CEUS and H-CEUS for both benign and malignant lesions(all p=0.000-0.008),but there were no significant differences in washout results(p=0.566 and p=0.684,respectively).For lesions 1-3 cm in size,the enhancement area,fill-in direction,and vascular architecture on C-CEUS and H-CEUS were significantly dif-ferent(all p=0.000),unlike for lesions 3-5 cm or>5 cm in size.For differentiation of malignant from benign FLLs in the 1-3 cm group,H-CEUS showed sensitivity,specific-ity,accuracy,and positive and negative predictive values of 92.86%,95.0%,96.3%,90.48%and 93.75%,respectively,which were higher than those for C-CEUS(75.0%,70.0%,77.78%,66.67%and 72.91%,respectively).Conclusions:H-CEUS provided more vascular information which could help differentiate malignant from benign FLLs,especially for lesions 1-3 cm in size.
基金supports from National Natural Science Foundation of China (Grant No.62205117,52275429)National Key Research and Development Program of China (Grant No.2021YFF0502700)+3 种基金Young Elite Scientists Sponsorship Program by CAST (Grant No.2022QNRC001)West Light Foundation of the Chinese Academy of Sciences (Grant No.xbzg-zdsys-202206)Knowledge Innovation Program of Wuhan-Shuguang,Innovation project of Optics Valley Laboratory (Grant No.OVL2021ZD002)Hubei Provincial Natural Science Foundation of China (Grant No.2022CFB792).
文摘Interactive holography offers unmatched levels of immersion and user engagement in the field of future display.Despite of the substantial progress has been made in dynamic meta-holography,the realization of real-time,highly smooth interactive holography remains a significant challenge due to the computational and display frame rate limitations.In this study,we introduced a dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates.To our knowledge,this is the first reported practical dynamic interactive metasurface holographic system.We spa-tially divided the metasurface device into multiple distinct channels,each projecting a reconstructed sub-pattern.The switching states of these channels were mapped to bitwise operations on a set of bit values,which avoids complex holo-gram computations,enabling an ultra-high computational frame rate.Our approach achieves a computational frame rate of 800 kHz and a display frame rate of 23 kHz on a low-power Raspberry Pi computational platform.According to this methodology,we demonstrated an interactive dynamic holographic Tetris game system that allows interactive gameplay,color display,and on-the-fly hologram creation.Our technology presents an inspiration for advanced dynamic meta-holography,which is promising for a broad range of applications including advanced human-computer interaction,real-time 3D visualization,and next-generation virtual and augmented reality systems.
基金Supported by National Defense Pre-research Foundation
文摘A very high frame rate camera is designed based on an innovative CCD driving method. The CCD driving method is mainly implemented on frame transfer CCDs. Asynchronous drive timing sequences are applied in the image and storage section of the CCDs. Several rows of the charge in the image section are binned onto the same row in the storage section, and there are the same number of images to be stored in the storage section before they are read out. Based on the new driving method, the frame transfer CCDs can work at a very high frame rate in acquiring burst images though the reading speed remains at a lower level. A very high frame rate camera is designed in this paper. The innovative CCD driving method is mainly of concern. An e2v’s CCD60 is adopted in the camera system, whose full size resolution is 128×128, and the up most frame rate is 1000 Hz in the conventional CCD driving method. By using the presented method, the CCD60 based imager is capable of operating at up to 40000 frames per second （fps） at a recognizable resolution of 128×32. Comparing cameras using traditional binning and region of interest technologies, the frame rate is normally less than 5000 fps while the resolution is only 32×32 left.
基金Supported by the Guide Project for Key Research and Development Foundation of Liaoning Province,No.2019JH8/10300008the 345 Talent Projectthe Liaoning Baiqianwan Talents Program.
文摘BACKGROUND Liver metastasis of duodenal gastrointestinal stromal tumor(GIST)is rare.Most reports mainly focus on its treatment and approaches to surgical resection,while details on its contrast-enhanced ultrasound(CEUS)findings are lacking.The diagnosis and imaging modalities for this condition remain challenging.CASE SUMMARY A 53-year-old Chinese man presented with mild signs and symptoms of the digestive tract.He underwent routine examinations after GIST surgery.Magnetic resonance imaging showed a 2.3 cm hepatic space-occupying lesion.All the laboratory test results were within normal limits.For further diagnostic confirmation,we conducted high frame rate CEUS(H-CEUS)and found a malignant perfusion pattern.Heterogeneous concentric hyper-enhancement,earlier wash-in than the liver parenchyma,and two irregular vessel columns could be observed at the periphery of the lesion during the arterial phase.Ultrasound-guided puncture biopsy was used to confirm the diagnosis of the lesion as liver metastasis of duodenal GIST.Imatinib was prescribed after biopsy,and the patient’s clinical course was monitored.CONCLUSION H-CEUS is useful for detecting microcirculation differences,wash-in patterns,and vascular morphogenesis and diagnosing liver metastasis of duodenal GIST.
文摘The orbital angular momentum(OAM)of light has been implemented as an information carrier in OAM holography.Holographic information can be multiplexed in theoretical unbounded OAM channels,promoting the applications of optically addressable dynamic display and high-security optical encryption.However,the frame-rate of the dynamic extraction of the information reconstruction process in OAM holography is physically determined by the switching speed of the incident OAM states,which is currently below 30 Hz limited by refreshing rate of the phase-modulation spatial light modulator(SLM).Here,based on a cross convolution with the spatial frequency of the OAM-multiplexing hologram,the spatial frequencies of an elaborately-designed amplitude distribution,namely amplitude decoding key,has been adopted for the extraction of three-dimensional holographic information encoded in a specific OAM information channel.We experimentally demonstrated a dynamic extraction frame rate of 100 Hz from an OAM multiplexing hologram with 10 information channels indicated by individual OAM values from-50 to 50.The new concept of cross convolution theorem can even provide the potential of parallel reproduction and distribution of information encoded in many OAM channels at various positions which boosts the capacity of information processing far beyond the traditional decoding methods.Thus,our results provide a holographic paradigm for high-speed 3D information processing,paving an unprecedented way to achieve the high-capacity short-range optical communication system.
基金National Natural Science Foundation of China(30227001)
文摘Frame rate is corresponding to the temporal resolution and the number of the pixels of the picture is corresponding to the spatial resolution. They are both very important for the researchers. The ideal image analysis and processing system should have high spatiotemporal characteristics, which is much expensive in practical use. A new method to enhance dynamic frame rate using multi-digital camera(DC) is proposed and the result shows that it could increase the frame rate effectively and decreases the cost in practical use.
基金Project (No. STE1093/1-1) supported by the German ResearchFoundation, Germany
文摘We propose a Rate-Distortion (RD) optimized strategy for frame-dropping and scheduling of multi-user conversa- tional and streaming videos. We consider a scenario where conversational and streaming videos share the forwarding resources at a network node. Two buffers are setup on the node to temporarily store the packets for these two types of video applications. For streaming video, a big buffer is used as the associated delay constraint of the application is moderate and a very small buffer is used for conversational video to ensure that the forwarding delay of every packet is limited. A scheduler is located behind these two buffers that dynamically assigns transmission slots on the outgoing link to the two buffers. Rate-distortion side information is used to perform RD-optimized frame dropping in case of node overload. Sharing the data rate on the outgoing link between the con- versational and the streaming videos is done either based on the fullness of the two associated buffers or on the mean incoming rates of the respective videos. Simulation results showed that our proposed RD-optimized frame dropping and scheduling ap- proach provides significant improvements in performance over the popular priority-based random dropping (PRD) technique.
文摘Most of the traditional methods are based on block motion compensation tending to involve heavy blocking artifacts in the interpolated frames. In this paper, a new frame interpolation method with pixel-level motion vector field （MVF） is proposed. Our method consists of the following four steps： （i） applying the pixel-level motion vectors （MVs） estimated by optical flow algorithm to eliminate blocking artifacts （ii） motion post-processing and super-sampling anti-aliasing to solve the problems caused by pixel-level MVs （iii） robust warping method to address collisions and holes caused by occlusions （iv） a new holes filling method using triangular mesh （HFTM） to reduce the artifacts caused by holes. Experimental results show that the proposed method can effectively alleviate the holes and blocking artifacts in interpolated frames, and outperforms existing methods both in terms of objective and subjective performances, especially for sequences with complex motions.
文摘A dynamic learning rate Gaussian mixture model（GMM）algorithm is proposed to deal with the problem of slow adaption of GMM in the case of moving object detection in the outdoor surveillance,especially in the presence of sudden illumination changes.The GMM is mostly used for detecting objects in complex scenes for intelligent monitoring systems.To solve this problem,a mixture Gaussian model has been built for each pixel in the video frame,and according to the scene change from the frame difference,the learning rate of GMM can be dynamically adjusted.The experiments show that the proposed method gives good results with an adaptive GMM learning rate when we compare it with GMM method with a fixed learning rate.The method was tested on a certain dataset,and tests in the case of sudden natural light changes show that our method has a better accuracy and lower false alarm rate.
基金Supported by the National Natural Science Foundation of China (No. 60972039)the Scientific Planning Project of Zhejiang Province entitled "Research and Development of Smart Antenna for the Next Generation Mobile Com-munications Based on TDD"the Young Staff Startup Research Foundation of Hangzhou Dianzi University entitled "Research on Key Technologies of Resource Allocation in Cognitive Radio Networks Based on Multicarrier Modulation"
文摘Efficient anti-jamming rateless coding based on cognitive Orthogonal Frequency Division Multiplexing (OFDM) modulation in Cognitive Radio Network (CRN) is mainly discussed. Rateless coding with small redundancy and low complexity is presented, and the optimal design methods of building rateless codes are also proposed. In CRN, anti-jamming rateless coding could recover the lost packets in parallel channels of cognitive OFDM, thus it protects Secondary Users (SUs) from the in-terference by Primary Users (PUs) efficiently. Frame Error Rate (FER) and throughput performance of SU employing anti-jamming rateless coding are analyzed in detail. Performance comparison between rateless coding and piecewise coding are also presented. It is shown that, anti-jamming rateless coding provides low FER and Word Error Rate (WER) performance with uniform sub-channel selection. Meanwhile, it is also verified that, in higher jamming rate and longer code redundancy scenario, rateless coding method could achieve better FER and throughput performance than another anti-jamming coding schemes.
基金Partially supported by Australian Air Force Office of Scientific Research(AFOSR)Grant(FA2386-13-1-4080)
文摘Frame processing method offers a model-based approach to Inverse Synthetic Aperture Radar(ISAR) imaging. It also provides a way to estimate the rotation rate of a non-cooperative target from radar returns via the frame operator properties. In this paper, the relationship between the best achievable ISAR image and the reconstructed image from radar returns was derived in the framework of Finite Frame Processing theory. We show that image defocusing caused by the use of an incorrect target rotation rate is interpreted under the FP method as a frame operator mismatch problem which causes energy dispersion. The unknown target rotation rate may be computed by optimizing the frame operator via a prominent point. Consequently, a prominent intensity maximization method in FP framework was proposed to estimate the underlying target rotation rate from radar returns. In addition, an image filtering technique was implemented to assist searching for a prominent point in practice. The proposed method is justified via a simulation analysis on the performance of FP imaging versus target rotation rate error.Effectiveness of the proposed method is also confirmed from real ISAR data experiments.
基金Supported by the National Natural Science Foundation of China(No.61271230,61472190)the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University(No.2013D02)the Open Research Fund of National Key Laboratory of Electromagnetic Environment,China Research Institute of Radiowave Propagation(No.201500013)
文摘The pilotless frame synchronization approach and implementations of LDPC code are the crucial issue of LDPC decoder. The Maximum-A-Posteriori probability( MAP) decoder has a perfect frame synchronization error rate( FSER) performance. In this paper,a theoretical derivation of the FSER performance of pilotless frame synchronization for LDPC code is presented. The FSER performance by theoretical analysis coincides well with that by simulation in additive white Gaussian channel and Rician fading channel. So it is estimated the FSER performance of an LDPC code by theoretical analysis can be used instead of the simulations which are much more time-consuming.
