A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,...A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,enabling the acquisition of full-process data of the fragment scattering process.However,mismatches between camera frame rates and target velocities can lead to long motion blur tails of high-speed fragment targets,resulting in low signal-to-noise ratios and rendering conventional detection algorithms ineffective in dynamic strong interference testing environments.In this study,we propose a detection framework centered on dynamic strong interference disturbance signal separation and suppression.We introduce a mixture Gaussian model constrained under a joint spatialtemporal-transform domain Dirichlet process,combined with total variation regularization to achieve disturbance signal suppression.Experimental results demonstrate that the proposed disturbance suppression method can be integrated with certain conventional motion target detection tasks,enabling adaptation to real-world data to a certain extent.Moreover,we provide a specific implementation of this process,which achieves a detection rate close to 100%with an approximate 0%false alarm rate in multiple sets of real target field test data.This research effectively advances the development of the field of damage parameter testing.展开更多
To overcome some drawbacks of Viterbi algorithm （VA）, such as exponential growing complexity of decoding, and its poor performance under bad channel conditions, some available known information must be used as cons...To overcome some drawbacks of Viterbi algorithm （VA）, such as exponential growing complexity of decoding, and its poor performance under bad channel conditions, some available known information must be used as constrained condition and apriori knowledge for decoding. A new constrained VA is proposed by adding con- straint bits directly for conventional codec. Compared with the conventional VA, under the bad channel condi- tion, the proposed scheme can improve the peak signal to noise ratio （PSNR） of the decoding image 2--10 dB by changing the number of constrained bits. Experimental results show that it is an efficient error-controlling way for the transmission of set partitioning in hierarchical trees （SPIHT） coded image.展开更多
Aiming at the problem in infrared image enhancement,a new method is given based on histogram.Using the gray characteristics of target,the upper-bound threshold is selected adaptively and the histogram is processed by ...Aiming at the problem in infrared image enhancement,a new method is given based on histogram.Using the gray characteristics of target,the upper-bound threshold is selected adaptively and the histogram is processed by the threshold.After choosing the gray transform function based on the gray level distribution of image,the gray transformation is done during histogram equalization.Finally,the enhanced image is obtained.Compared with histogram equalization(HE),histogram double equalization(HDE) and plateau histogram equalization(PE),the simulation results demonstrate that the image enhancement effect of this method has obvious superiority.At the same time,its operation speed is fast and real-time ability is excellent.展开更多
Hepatocellular carcinoma(HCC)is a leading cause of morbidity and mortality worldwide,with rising clinical and economic burden as incidence increases.There are a multitude of evolving treatment options,including locore...Hepatocellular carcinoma(HCC)is a leading cause of morbidity and mortality worldwide,with rising clinical and economic burden as incidence increases.There are a multitude of evolving treatment options,including locoregional therapies which can be used alone,in combination with each other,or in combination with systemic therapy.These treatment options have shown to be effective in achieving remission,controlling tumor progression,improving disease free and overall survival in patients who cannot undergo resection and providing a bridge to transplant by debulking tumor burden to downstage patients.Following locoregional therapy(LRT),it is crucial to provide treatment response assessment to guide management and liver transplant candidacy.Therefore,Liver Imaging Reporting and Data Systems(LI-RADS)Treatment Response Algorithm(TRA)was created to provide a standardized assessment of HCC following LRT.LIRADS TRA provides a step by step approach to evaluate each lesion independently for accurate tumor assessment.In this review,we provide an overview of different locoregional therapies for HCC,describe the expected post treatment imaging appearance following treatment,and review the LI-RADS TRA with guidance for its application in clinical practice.Unique to other publications,we will also review emerging literature supporting the use of LI-RADS for assessment of HCC treatment response after LRT.展开更多
Typical fundus photography produces a two-dimensional image.This makes it difficult to observe the microvascular and neural abnormalities,because the depth of the image is missing.To provide depth appreciation,we deve...Typical fundus photography produces a two-dimensional image.This makes it difficult to observe the microvascular and neural abnormalities,because the depth of the image is missing.To provide depth appreciation,we develop a single-channel stereoscopic fundus video imaging sys-tem based on a rotating refractor.With respect to the pupil center,the rotating refractor laterally displaces the optical path and the illumination.This allows standard monocular fundus cameras to generate stereo-parallax and image disparity through sequential image acquisition.We opti-mize our imaging system,characterize the stereo-base,and image an eyeball model and a rabbit eye.When virtual realities are considered,our imaging system can be a simple yet efficient technique to provide depth perception in a virtual space that allows users to perceive abnor-malities in the eye fundus.展开更多
In this paper,an image processing method for improving the quality of optical coherence tomography(OCT)images is proposed.Wavelet denoising based on context modeling and contrast enhancement by means of the contrast m...In this paper,an image processing method for improving the quality of optical coherence tomography(OCT)images is proposed.Wavelet denoising based on context modeling and contrast enhancement by means of the contrast measure in the wavelet domain is carried out on the OCT images in succession.Three parameters are selected to assess the effectiveness of the method.It is shown from the results that the proposed method can not only enhance the contrast of images,but also improve signal-to-noise ratio.Compared with two other typical algorithms,it has the best visual effect.展开更多
Multispectral time delay and integration charge coupled device （TDICCD） image compression requires a low- complexity encoder because it is usually completed on board where the energy and memory are limited. The Cons...Multispectral time delay and integration charge coupled device （TDICCD） image compression requires a low- complexity encoder because it is usually completed on board where the energy and memory are limited. The Consultative Committee for Space Data Systems （CCSDS） has proposed an image data compression （CCSDS-IDC） algorithm which is so far most widely implemented in hardware. However, it cannot reduce spectral redundancy in mukispectral images. In this paper, we propose a low-complexity improved CCSDS-IDC （ICCSDS-IDC）-based distributed source coding （DSC） scheme for multispectral TDICCD image consisting of a few bands. Our scheme is based on an ICCSDS-IDC approach that uses a bit plane extractor to parse the differences in the original image and its wavelet transformed coefficient. The output of bit plane extractor will be encoded by a first order entropy coder. Low-density parity-check-based Slepian-Wolf （SW） coder is adopted to implement the DSC strategy. Experimental results on space multispectral TDICCD images show that the proposed scheme significantly outperforms the CCSDS-IDC-based coder in each band.展开更多
A novel analytical imaging algorithm is proposed for the strip-map mode of airborne bistatic squint SAR with unparallel trajectories. The algorithm derives the two-dimensional （2D） spectrum formula of the point targ...A novel analytical imaging algorithm is proposed for the strip-map mode of airborne bistatic squint SAR with unparallel trajectories. The algorithm derives the two-dimensional （2D） spectrum formula of the point target echo by using the contribution ratios of Doppler frequency modulation ratios of the transmitter and receiver as the weighting coefficients. Through decoupling the target position against the tracks of the transmitter and receiver, the range parameter and the azimuth one in the spectrum formula are separated. In 2D frequency domain, 2D Chirp-Z transform （2D-CZT） is applied to correcting the migrations of the echo along the range and azimuth after the bistatic deformation term has been compensated, so the target image is precisely focused. The advantage of the algorithm is easy to be expanded to the virtual wide swath by blocking the radar data along the range and azimuth to limit the 2D residual migrations. Simulation results confirm the validity of the 2D-CZT algorithm.展开更多
Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biologic...Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biological fuids of various human organs has been developed and experimentally tested.The coordinate distributions of phase and amplitude anisotropy of bile films and synovial fuid taken from the knee joint are determined and statistically analyzed.Criteria(statistical moments of 3rd and 4th orders)of differential diagnostics of early stages of cholelithiasis and septic arthritis of the knee joint with excellent balanced accuracy were determined.Data on the diagnostic fficiency of the Jones matrix tomography method for polyerystalline plasma(liver disease),urine(albuminuria)and cytological smears(cervical cancer)are presented.展开更多
This paper describes a person identifcation method for a mobile robot which performs specifc person following under dynamic complicated environments like a school canteen where many persons exist.We propose a distance...This paper describes a person identifcation method for a mobile robot which performs specifc person following under dynamic complicated environments like a school canteen where many persons exist.We propose a distance-dependent appearance model which is based on scale-invariant feature transform（SIFT） feature.SIFT is a powerful image feature that is invariant to scale and rotation in the image plane and also robust to changes of lighting condition.However,the feature is weak against afne transformations and the identifcation power will thus be degraded when the pose of a person changes largely.We therefore use a set of images taken from various directions to cope with pose changes.Moreover,the number of SIFT feature matches between the model and an input image will decrease as the person becomes farther away from the camera.Therefore,we also use a distance-dependent threshold.The person following experiment was conducted using an actual mobile robot,and the quality assessment of person identifcation was performed.展开更多
High resolution optical endoscopes are increasingly used in diagnosis of various medical condi-tions of internal organs,such as the cervix and gastrointestinal(GI)tracts,but they are too expensive for use in resource ...High resolution optical endoscopes are increasingly used in diagnosis of various medical condi-tions of internal organs,such as the cervix and gastrointestinal(GI)tracts,but they are too expensive for use in resource poor settings.On the other hand,smartphones with high resolution cameras and Internet access have become more affordable,enabling them to difuse into most rural areas and developing countries in the past decade.In this paper,we describe a smartphone microendoscope that can take fuorescence images with a spatial resolution of 3.1 pum.Images collected from ex vivo,in vnitro and in vivo samples using the device are also presented.The compact and cost-effective smart phone microendosoope may be envisaged as a powerful tool for detecting pre cancerous lesions of internal organs in low and middle income countries(LMICs).展开更多
A single-image passive ranging and three-dimensional(3 D)imaging system with chiral phase encoding was proposed in 2011[Opt.Lett.36,115(2011)].A new theoretical analysis of the system in space domain is presented in t...A single-image passive ranging and three-dimensional(3 D)imaging system with chiral phase encoding was proposed in 2011[Opt.Lett.36,115(2011)].A new theoretical analysis of the system in space domain is presented in this paper.We deduce the analytic relationships between the object distance and the point spread function,and between the object distance and the encoded image,respectively.Both the point spread function and the processed spectrum of the encoded image have two spots,which will rotate with the variation of the object distance.Then the depth map is extracted from the encoded image and it can be used to set up 3 D images.The theoretical analysis is verified by a wavefront coding system with a chiral phase which is generated by a phase-only liquid-crystal spatial light modulator.The phase generated by the liquid-crystal spatial light modulator is more flexible than the fixed phase mask and can be adjusted in real time.It is especially suitable for observing the object with a large depth of field.展开更多
3D live imaging is important for better understanding of biological processes.To obtain biological dynamic process,high imaging speed is required.In order to improve speed in 3D live imaging,simultaneous imaging of mu...3D live imaging is important for better understanding of biological processes.To obtain biological dynamic process,high imaging speed is required.In order to improve speed in 3D live imaging,simultaneous imaging of multiple planes throughout a 3D volume has been proposed.However,a main disadvantage of this method is the cross-talk from neighboring imaging planes.In this paper,we propose an optimization method to suppress background from neighboring imaging planes.A D-aperture is used to generate multiple light sheets.An optimization method to suppress background is presented.The simulation results demonstrated that the proposed method can be used to suppress the effectiveness of background from neighboring light sheets.展开更多
We present a novel optical sensor to acquire simultaneously functional near-infrared imaging(fNIRI)and functional magnetic resonance imaging(fMRI)data with an improved handling and direct localization in the MRI compa...We present a novel optical sensor to acquire simultaneously functional near-infrared imaging(fNIRI)and functional magnetic resonance imaging(fMRI)data with an improved handling and direct localization in the MRI compared to available sensors.Quantitative phantom and interference measurements showed that both methods can be combined without reciprocal adverse effects.The direct localization of the optical sensor on MR images acquired with a T1-weighted echo sequence simplifies the co-registration of NIRI and MRI data.In addition,the optical sensor is simple to attach,which is crucial for measurements on vulnerable subjects.The fNIRI and T2^(*)-weighted fMRI data of a cerebral activation were simultaneously acquired proving the practicability of the setup.展开更多
Scintillators are high-density luminescent materials that convert X-rays to visible light. Thallium doped cesium iodide (CsI:Tl) scintillation materials are widely used as converters for X-rays into visible light, wit...Scintillators are high-density luminescent materials that convert X-rays to visible light. Thallium doped cesium iodide (CsI:Tl) scintillation materials are widely used as converters for X-rays into visible light, with very high conversion efficiency of 64.000 optical photons/MeV. CsI:Tl crystals are commercially available, but, the possibility of developing these crystals into different geometric shapes, meeting the need for coupling the photosensor and reducing cost, makes this material very attractive for scientific research. The objective of this work was to study the feasibility of using radiation sensors, scintillators type, developed for use in imaging systems for X-rays. In this paper, the CsI:Tl scintillator crystal with nominal concentration of the 10-3 M was grown by the vertical Bridgman technique. The imaging performance of CsI:Tl scintillator was studied as a function of the design type and thickness, since it interferes with the light scattering and, hence, the detection efficiency plus final image resolution. The result of the diffraction X-ray analysis in the grown crystals was consistent with the pattern of a face-centered cubic (fcc) crystal structure. Slices 25 × 2 × 3 mm3 (length, thickness, height) of the crystal and mini crystals of 1 × 2 × 3 mm3 (length, thickness, height) were used for comparison in the imaging systems for X-rays. With these crystals scintillators, images of undesirable elements, such as metals in food packaging, were obtained. One-dimensional array of photodiodes and the photosensor CCD (Coupled Charge Device) component were used. In order to determine the ideal thickness of the slices of the scintillator crystal CsI:Tl, Monte Carlo method was used.展开更多
Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of P...Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of PCDs based X-ray imaging systems.Starting with an introduction of X-ray single photon detection mechanism,the brief review first describes tw o major advantages of utilizing PCDs: photon energy resolving capability and electronic noise elimination. Compared to energy integrating detectors(EIDs),the aforementioned advantages make PCDs more favorable in X-ray imaging with profound benefits such as enhanced tissue contrast,decreased image noise,increased signal to noise ratio,decreased radiation dose to the small animals and patients,and more accurate material decomposition. The utilizations of PCDs in X-ray projection radiography and computed tomography(CT)including micro-CT,dedicated breast CT,K-edge CT,and clinical CT are then review ed for the imaging applications ranging from phantoms to small animals and humans. In addition,optimization methods aiming to improve the imaging performance using PCDs are briefly review ed. PCDs are not flaw less though,and their limitations are also discussed in this review. Nevertheless,PCDs may continuously contribute to the advancement of X-ray imaging techniques in future preclinical and clinical applications.展开更多
The next generation of smart imaging and vision systems will require compact and tunable optical computing hardware to perform high-speed and low-power image processing.These requirements are driving the development o...The next generation of smart imaging and vision systems will require compact and tunable optical computing hardware to perform high-speed and low-power image processing.These requirements are driving the development of computing metasurfaces to realize efficient front-end analog optical pre-processors,especially for edge detection capability.Yet,there is still a lack of reconfigurable or programmable schemes,which may drastically enhance the impact of these devices at the system level.Here,we propose and experimentally demonstrate a reconfigurable flat optical image processor using low-loss phase-change nonlocal metasurfaces.The metasurface is configured to realize different transfer functions in spatial frequency space,when transitioning the phase-change material between its amorphous and crystalline phases.This enables edge detection and bright field imaging modes on the same device.The metasurface is compatible with a large numerical aperture of~0.5,making it suitable for high resolution coherent optical imaging microscopy.The concept of phase-change reconfigurable nonlocal metasurfaces may enable emerging applications of artificial intelligence-assisted imaging and vision devices with switchable multitasking.展开更多
Infrared images are firstly analyzed using the multifractal theory so that the singularity of each pixel can be extracted from the images. The multifractal spectrum is then estimated, which can reflect overall charact...Infrared images are firstly analyzed using the multifractal theory so that the singularity of each pixel can be extracted from the images. The multifractal spectrum is then estimated, which can reflect overall characteristic of an infrared image. Thus the edge and texture of an infrared image can be accurately extracted based on the singularity of each pixel and the multifractal spectrum. Finally the edge pixels are classified and enhanced in accordance with the sensitivity of human visual system to the edge profile of an infrared image. The experimental results obtained by this approach are compared with those obtained by other methods. It is found that the proposed approach can be used to highlight the edge area of an infrared image to make an infrared image more suitable for observation by human eyes.展开更多
In this letter, we develope a control and image processing system for Streak Tube Imaging Lidar （STIL）. In the system, the data acquisition card control and the software interface are programmed in Visual Basic （VB...In this letter, we develope a control and image processing system for Streak Tube Imaging Lidar （STIL）. In the system, the data acquisition card control and the software interface are programmed in Visual Basic （VB） while the image processing is finished by MATLAB. A STIL imaging experiment is carried out in the laboratory. We obtained the intensity and range images of targets with pseudo color by image processing and reconstruction for a set of raw streak images of targets at different distances acquired by STIL. The range resolution is better than 2 centimeters.展开更多
The image quality evaluation in fiber-optic image bundles was addressed by the modulation transfer function (MTF). With the definition of the contrast transfer function (CTF), the MTF model of line-array fiber-optic i...The image quality evaluation in fiber-optic image bundles was addressed by the modulation transfer function (MTF). With the definition of the contrast transfer function (CTF), the MTF model of line-array fiber-optic image bundles was established and analyzed numerically. The average MTF was carefully evaluated by considering the influence of phase match on the MTF between input pattern and fiber-optic image bundles. In this paper, the average MTF is mean arithmetical value on the MTFs of eight different phases. The results show that, for certain fiber diameter and spatial frequency, the relationship between the core diameter and the average MTF is inverse proportion; for certain fiber cladding thickness, the relationship between the core diameter and the average MTF is also inverse proportion. And at Nyquist frequencv. the MTF value is near 0.5.展开更多
文摘A measurement system for the scattering characteristics of warhead fragments based on high-speed imaging systems offers advantages such as simple deployment,flexible maneuverability,and high spatiotemporal resolution,enabling the acquisition of full-process data of the fragment scattering process.However,mismatches between camera frame rates and target velocities can lead to long motion blur tails of high-speed fragment targets,resulting in low signal-to-noise ratios and rendering conventional detection algorithms ineffective in dynamic strong interference testing environments.In this study,we propose a detection framework centered on dynamic strong interference disturbance signal separation and suppression.We introduce a mixture Gaussian model constrained under a joint spatialtemporal-transform domain Dirichlet process,combined with total variation regularization to achieve disturbance signal suppression.Experimental results demonstrate that the proposed disturbance suppression method can be integrated with certain conventional motion target detection tasks,enabling adaptation to real-world data to a certain extent.Moreover,we provide a specific implementation of this process,which achieves a detection rate close to 100%with an approximate 0%false alarm rate in multiple sets of real target field test data.This research effectively advances the development of the field of damage parameter testing.
文摘To overcome some drawbacks of Viterbi algorithm （VA）, such as exponential growing complexity of decoding, and its poor performance under bad channel conditions, some available known information must be used as constrained condition and apriori knowledge for decoding. A new constrained VA is proposed by adding con- straint bits directly for conventional codec. Compared with the conventional VA, under the bad channel condi- tion, the proposed scheme can improve the peak signal to noise ratio （PSNR） of the decoding image 2--10 dB by changing the number of constrained bits. Experimental results show that it is an efficient error-controlling way for the transmission of set partitioning in hierarchical trees （SPIHT） coded image.
文摘Aiming at the problem in infrared image enhancement,a new method is given based on histogram.Using the gray characteristics of target,the upper-bound threshold is selected adaptively and the histogram is processed by the threshold.After choosing the gray transform function based on the gray level distribution of image,the gray transformation is done during histogram equalization.Finally,the enhanced image is obtained.Compared with histogram equalization(HE),histogram double equalization(HDE) and plateau histogram equalization(PE),the simulation results demonstrate that the image enhancement effect of this method has obvious superiority.At the same time,its operation speed is fast and real-time ability is excellent.
文摘Hepatocellular carcinoma(HCC)is a leading cause of morbidity and mortality worldwide,with rising clinical and economic burden as incidence increases.There are a multitude of evolving treatment options,including locoregional therapies which can be used alone,in combination with each other,or in combination with systemic therapy.These treatment options have shown to be effective in achieving remission,controlling tumor progression,improving disease free and overall survival in patients who cannot undergo resection and providing a bridge to transplant by debulking tumor burden to downstage patients.Following locoregional therapy(LRT),it is crucial to provide treatment response assessment to guide management and liver transplant candidacy.Therefore,Liver Imaging Reporting and Data Systems(LI-RADS)Treatment Response Algorithm(TRA)was created to provide a standardized assessment of HCC following LRT.LIRADS TRA provides a step by step approach to evaluate each lesion independently for accurate tumor assessment.In this review,we provide an overview of different locoregional therapies for HCC,describe the expected post treatment imaging appearance following treatment,and review the LI-RADS TRA with guidance for its application in clinical practice.Unique to other publications,we will also review emerging literature supporting the use of LI-RADS for assessment of HCC treatment response after LRT.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(2019R1A2C2091068).
文摘Typical fundus photography produces a two-dimensional image.This makes it difficult to observe the microvascular and neural abnormalities,because the depth of the image is missing.To provide depth appreciation,we develop a single-channel stereoscopic fundus video imaging sys-tem based on a rotating refractor.With respect to the pupil center,the rotating refractor laterally displaces the optical path and the illumination.This allows standard monocular fundus cameras to generate stereo-parallax and image disparity through sequential image acquisition.We opti-mize our imaging system,characterize the stereo-base,and image an eyeball model and a rabbit eye.When virtual realities are considered,our imaging system can be a simple yet efficient technique to provide depth perception in a virtual space that allows users to perceive abnor-malities in the eye fundus.
基金supported by the National Natural Science Foundation of China(Grant Nos.60637020 and 60677012)the Tianjin Foundation of Natural Science(No.09JCZDJC18300).
文摘In this paper,an image processing method for improving the quality of optical coherence tomography(OCT)images is proposed.Wavelet denoising based on context modeling and contrast enhancement by means of the contrast measure in the wavelet domain is carried out on the OCT images in succession.Three parameters are selected to assess the effectiveness of the method.It is shown from the results that the proposed method can not only enhance the contrast of images,but also improve signal-to-noise ratio.Compared with two other typical algorithms,it has the best visual effect.
基金supported by the National High Technology Research and Development Program of China (Grant No. 863-2-5-1-13B)
文摘Multispectral time delay and integration charge coupled device （TDICCD） image compression requires a low- complexity encoder because it is usually completed on board where the energy and memory are limited. The Consultative Committee for Space Data Systems （CCSDS） has proposed an image data compression （CCSDS-IDC） algorithm which is so far most widely implemented in hardware. However, it cannot reduce spectral redundancy in mukispectral images. In this paper, we propose a low-complexity improved CCSDS-IDC （ICCSDS-IDC）-based distributed source coding （DSC） scheme for multispectral TDICCD image consisting of a few bands. Our scheme is based on an ICCSDS-IDC approach that uses a bit plane extractor to parse the differences in the original image and its wavelet transformed coefficient. The output of bit plane extractor will be encoded by a first order entropy coder. Low-density parity-check-based Slepian-Wolf （SW） coder is adopted to implement the DSC strategy. Experimental results on space multispectral TDICCD images show that the proposed scheme significantly outperforms the CCSDS-IDC-based coder in each band.
基金Foundation item： Anhui Province Natural Science Foundation of China （11040606M126）
文摘A novel analytical imaging algorithm is proposed for the strip-map mode of airborne bistatic squint SAR with unparallel trajectories. The algorithm derives the two-dimensional （2D） spectrum formula of the point target echo by using the contribution ratios of Doppler frequency modulation ratios of the transmitter and receiver as the weighting coefficients. Through decoupling the target position against the tracks of the transmitter and receiver, the range parameter and the azimuth one in the spectrum formula are separated. In 2D frequency domain, 2D Chirp-Z transform （2D-CZT） is applied to correcting the migrations of the echo along the range and azimuth after the bistatic deformation term has been compensated, so the target image is precisely focused. The advantage of the algorithm is easy to be expanded to the virtual wide swath by blocking the radar data along the range and azimuth to limit the 2D residual migrations. Simulation results confirm the validity of the 2D-CZT algorithm.
基金support of the Academy of Finland(grant projects:311698)support of INFOTECH grant project,as well as the MEPhI Academic Excellence Project(Contract No.02.a03.21.0005)the National Research Tomsk State University Academic D.I.Mendeleev Fund Program.
文摘Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biological fuids of various human organs has been developed and experimentally tested.The coordinate distributions of phase and amplitude anisotropy of bile films and synovial fuid taken from the knee joint are determined and statistically analyzed.Criteria(statistical moments of 3rd and 4th orders)of differential diagnostics of early stages of cholelithiasis and septic arthritis of the knee joint with excellent balanced accuracy were determined.Data on the diagnostic fficiency of the Jones matrix tomography method for polyerystalline plasma(liver disease),urine(albuminuria)and cytological smears(cervical cancer)are presented.
基金supported by JSPS KAKENHI (No.23700203) and NEDO Intelligent RT Software Project
文摘This paper describes a person identifcation method for a mobile robot which performs specifc person following under dynamic complicated environments like a school canteen where many persons exist.We propose a distance-dependent appearance model which is based on scale-invariant feature transform（SIFT） feature.SIFT is a powerful image feature that is invariant to scale and rotation in the image plane and also robust to changes of lighting condition.However,the feature is weak against afne transformations and the identifcation power will thus be degraded when the pose of a person changes largely.We therefore use a set of images taken from various directions to cope with pose changes.Moreover,the number of SIFT feature matches between the model and an input image will decrease as the person becomes farther away from the camera.Therefore,we also use a distance-dependent threshold.The person following experiment was conducted using an actual mobile robot,and the quality assessment of person identifcation was performed.
文摘High resolution optical endoscopes are increasingly used in diagnosis of various medical condi-tions of internal organs,such as the cervix and gastrointestinal(GI)tracts,but they are too expensive for use in resource poor settings.On the other hand,smartphones with high resolution cameras and Internet access have become more affordable,enabling them to difuse into most rural areas and developing countries in the past decade.In this paper,we describe a smartphone microendoscope that can take fuorescence images with a spatial resolution of 3.1 pum.Images collected from ex vivo,in vnitro and in vivo samples using the device are also presented.The compact and cost-effective smart phone microendosoope may be envisaged as a powerful tool for detecting pre cancerous lesions of internal organs in low and middle income countries(LMICs).
基金Project supported by the National Natural Science Foundation of China(Grant No.61205158)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY15F050013)
文摘A single-image passive ranging and three-dimensional(3 D)imaging system with chiral phase encoding was proposed in 2011[Opt.Lett.36,115(2011)].A new theoretical analysis of the system in space domain is presented in this paper.We deduce the analytic relationships between the object distance and the point spread function,and between the object distance and the encoded image,respectively.Both the point spread function and the processed spectrum of the encoded image have two spots,which will rotate with the variation of the object distance.Then the depth map is extracted from the encoded image and it can be used to set up 3 D images.The theoretical analysis is verified by a wavefront coding system with a chiral phase which is generated by a phase-only liquid-crystal spatial light modulator.The phase generated by the liquid-crystal spatial light modulator is more flexible than the fixed phase mask and can be adjusted in real time.It is especially suitable for observing the object with a large depth of field.
基金This work is supported by the Vietnam National Foundation for Science and Technology Development(NAFOSTED)under Grant number(103.03-2018.08).
文摘3D live imaging is important for better understanding of biological processes.To obtain biological dynamic process,high imaging speed is required.In order to improve speed in 3D live imaging,simultaneous imaging of multiple planes throughout a 3D volume has been proposed.However,a main disadvantage of this method is the cross-talk from neighboring imaging planes.In this paper,we propose an optimization method to suppress background from neighboring imaging planes.A D-aperture is used to generate multiple light sheets.An optimization method to suppress background is presented.The simulation results demonstrated that the proposed method can be used to suppress the effectiveness of background from neighboring light sheets.
基金The authors gratefully acknowledge the support of the Swiss National Foundation(National Research Programme NRP 57)and like to thank Andreas Metz for his dedication.We thank Klaas Enno Stephan for supporting this study and Philips Healthcare for technical andfinancial support.We like to address special thanks to Elisabeth Moore from Philips Healthcare for providing and answering questions about the MRI stability test postprocessing software,to Dennis Hueber from ISS Inc.for answering questions about the ISS OxiplexTSTM and to Cornelia Hagmann for proofreading the manuscript.
文摘We present a novel optical sensor to acquire simultaneously functional near-infrared imaging(fNIRI)and functional magnetic resonance imaging(fMRI)data with an improved handling and direct localization in the MRI compared to available sensors.Quantitative phantom and interference measurements showed that both methods can be combined without reciprocal adverse effects.The direct localization of the optical sensor on MR images acquired with a T1-weighted echo sequence simplifies the co-registration of NIRI and MRI data.In addition,the optical sensor is simple to attach,which is crucial for measurements on vulnerable subjects.The fNIRI and T2^(*)-weighted fMRI data of a cerebral activation were simultaneously acquired proving the practicability of the setup.
基金FAPESP(Foundation Research of the State of Sao Paulo)for financial support.
文摘Scintillators are high-density luminescent materials that convert X-rays to visible light. Thallium doped cesium iodide (CsI:Tl) scintillation materials are widely used as converters for X-rays into visible light, with very high conversion efficiency of 64.000 optical photons/MeV. CsI:Tl crystals are commercially available, but, the possibility of developing these crystals into different geometric shapes, meeting the need for coupling the photosensor and reducing cost, makes this material very attractive for scientific research. The objective of this work was to study the feasibility of using radiation sensors, scintillators type, developed for use in imaging systems for X-rays. In this paper, the CsI:Tl scintillator crystal with nominal concentration of the 10-3 M was grown by the vertical Bridgman technique. The imaging performance of CsI:Tl scintillator was studied as a function of the design type and thickness, since it interferes with the light scattering and, hence, the detection efficiency plus final image resolution. The result of the diffraction X-ray analysis in the grown crystals was consistent with the pattern of a face-centered cubic (fcc) crystal structure. Slices 25 × 2 × 3 mm3 (length, thickness, height) of the crystal and mini crystals of 1 × 2 × 3 mm3 (length, thickness, height) were used for comparison in the imaging systems for X-rays. With these crystals scintillators, images of undesirable elements, such as metals in food packaging, were obtained. One-dimensional array of photodiodes and the photosensor CCD (Coupled Charge Device) component were used. In order to determine the ideal thickness of the slices of the scintillator crystal CsI:Tl, Monte Carlo method was used.
基金supported in part by a grant from the University of Oklahoma Charles and Peggy Stephenson Cancer Center funded by the Oklahoma Tobacco Settlement Endowment Trust
文摘Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of PCDs based X-ray imaging systems.Starting with an introduction of X-ray single photon detection mechanism,the brief review first describes tw o major advantages of utilizing PCDs: photon energy resolving capability and electronic noise elimination. Compared to energy integrating detectors(EIDs),the aforementioned advantages make PCDs more favorable in X-ray imaging with profound benefits such as enhanced tissue contrast,decreased image noise,increased signal to noise ratio,decreased radiation dose to the small animals and patients,and more accurate material decomposition. The utilizations of PCDs in X-ray projection radiography and computed tomography(CT)including micro-CT,dedicated breast CT,K-edge CT,and clinical CT are then review ed for the imaging applications ranging from phantoms to small animals and humans. In addition,optimization methods aiming to improve the imaging performance using PCDs are briefly review ed. PCDs are not flaw less though,and their limitations are also discussed in this review. Nevertheless,PCDs may continuously contribute to the advancement of X-ray imaging techniques in future preclinical and clinical applications.
基金supported by European Union’s Horizon 2020 research and innovation program(Grant No.101017237,PHOENICS Project)European Union’s EIC Pathfinder program(Grant No.101046878,HYBRAIN Project and No.101098717 RESPITE Project)+1 种基金funded in part by the UKRI[EP/T023899/1,EP/R001677/1,EP/W003341/1 and EP/W022931/1]funding from the Marie Sklodowska-Curie Individual Fellowship 101068089(METASCALE).
文摘The next generation of smart imaging and vision systems will require compact and tunable optical computing hardware to perform high-speed and low-power image processing.These requirements are driving the development of computing metasurfaces to realize efficient front-end analog optical pre-processors,especially for edge detection capability.Yet,there is still a lack of reconfigurable or programmable schemes,which may drastically enhance the impact of these devices at the system level.Here,we propose and experimentally demonstrate a reconfigurable flat optical image processor using low-loss phase-change nonlocal metasurfaces.The metasurface is configured to realize different transfer functions in spatial frequency space,when transitioning the phase-change material between its amorphous and crystalline phases.This enables edge detection and bright field imaging modes on the same device.The metasurface is compatible with a large numerical aperture of~0.5,making it suitable for high resolution coherent optical imaging microscopy.The concept of phase-change reconfigurable nonlocal metasurfaces may enable emerging applications of artificial intelligence-assisted imaging and vision devices with switchable multitasking.
基金supported by the Natural Science Foundation of Heilongjiang Province under Grant No. F200818
文摘Infrared images are firstly analyzed using the multifractal theory so that the singularity of each pixel can be extracted from the images. The multifractal spectrum is then estimated, which can reflect overall characteristic of an infrared image. Thus the edge and texture of an infrared image can be accurately extracted based on the singularity of each pixel and the multifractal spectrum. Finally the edge pixels are classified and enhanced in accordance with the sensitivity of human visual system to the edge profile of an infrared image. The experimental results obtained by this approach are compared with those obtained by other methods. It is found that the proposed approach can be used to highlight the edge area of an infrared image to make an infrared image more suitable for observation by human eyes.
基金supported by the Fundamental Research Funds for the Central Universities(No.HIT.BRET.2010014)the Science and Technology Planning of Shandong Province,China(No.2011GHY11514)
文摘In this letter, we develope a control and image processing system for Streak Tube Imaging Lidar （STIL）. In the system, the data acquisition card control and the software interface are programmed in Visual Basic （VB） while the image processing is finished by MATLAB. A STIL imaging experiment is carried out in the laboratory. We obtained the intensity and range images of targets with pseudo color by image processing and reconstruction for a set of raw streak images of targets at different distances acquired by STIL. The range resolution is better than 2 centimeters.
基金This work was supported by the National Natu- ral Science Foundation of China (No. 60378015) the Innovation Foundation of Chinese Academy of Sciences (No. C02L07Z).
文摘The image quality evaluation in fiber-optic image bundles was addressed by the modulation transfer function (MTF). With the definition of the contrast transfer function (CTF), the MTF model of line-array fiber-optic image bundles was established and analyzed numerically. The average MTF was carefully evaluated by considering the influence of phase match on the MTF between input pattern and fiber-optic image bundles. In this paper, the average MTF is mean arithmetical value on the MTFs of eight different phases. The results show that, for certain fiber diameter and spatial frequency, the relationship between the core diameter and the average MTF is inverse proportion; for certain fiber cladding thickness, the relationship between the core diameter and the average MTF is also inverse proportion. And at Nyquist frequencv. the MTF value is near 0.5.
