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IEEE International conference on image Processing

作者： v. L. Lo R. P. Millane R. L. Kingston Computational Imaging Group Department Electrical & Computer Eng. University of Canterbury Christchurch New Zealand School of Biological Sciences University of Auckland Auckland New Zealand

The envelope problem in macromolecular x-ray crystallography involves determining the boundary of a molecule from measurements of amplitudes of x-rays diffracted from a crystalline specimen. This represents a highly underdetermined image reconstruction problem with a large number of degrees of freedom. We regularize the problem by applying binary and connectivity constraints to the image, and seek the solution using the method of iterated projections. However, since the constraints are highly non-convex, the usual methods of generalized projections are not effective. We use the difference map projection algorithm and show that this is effective with simulated diffraction data from a protein envelope.

关键词： X-ray diffraction image reconstruction X-ray imaging Electrons Projection algorithms Atomic measurements Crystallography Crystallization Proteins Density functional theory

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A robust framework for GeoTime cube

A robust framework for GeoTime cube

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IEEE International conference on image Processing

作者： v. Toujas M. Donias D. Jeantet S. Guillon Y. Berthoumieu Laboratoire IMS UMR 5218Groupe SignalENSEIRBENSCPB Université Bordeaux Talence France TOTAL CSTJF Pau France

This paper presents a robust unsupervised framework for 3D seismic data flattening. The resulting volume, called GeoTime cube, brings to light history of sedimentary deposits which is a key issue in petroleum prospecting. The proposed method makes it possible to obtain the transformation by transcribing fundamental principles of geophysics in image processing. The first step is a sedimentary layer reconstruction, the second one consists in numbering them according to their relative geological age and the last one computes a transformation in order to clearly represent them in a flattened way. Finally, the results obtained by our method compared to an existing one show that many relevant information can be extracted from GeoTime cubes and the final flattened data enhances the seismic structures identification.

关键词： Robustness Geology data mining Surface reconstruction Stacking Petroleum image processing image reconstruction Geophysics computing Acoustic imaging

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Pulse radiolocation by means of two-dimensional antenna arrays

Pulse radiolocation by means of two-dimensional antenna arra...

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International conference on Ultrawideband and Ultrashort Impulse Signals, UWBUSIS

作者： O. v. Kazansky N. N. Kolchigin A. S. Kutzenko V.N. Karazin Kharkiv National University Kharkiv Ukraine

A method for reconstruction of earth surface and detection adjacent objects from redundant data and by means two dimensional antennas array as transmitting and receiving systems is described in this paper. An interpre... 详细信息

关键词： Antenna arrays Radar scattering Surface reconstruction Optical scattering image reconstruction Earth Radar antennas Optical surface waves Ultra wideband technology Object detection

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Conclusions from an experimental 3D Ultrasound Computer Tomograph

Conclusions from an experimental 3D Ultrasound Computer Tomo...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Nicole v. Ruiter Gregor F. Schwarzenberg Michael Zapf Hartmut Gemmeke Forschungszentrum Karlsruhe Institute for Data Processing and Electronics Karlsruhe Germany

Ultrasound Computer Tomography (USCT) records the interaction of ultrasonic waves with an imaged object from many different angles. The main advantage of such a system is simultaneous recording of reflection, absorption and speed of sound images, and higher image quality with fast data acquisition. Until now, it was not feasible to build a 3D USCT due to the high demands on the required number of transducers, high data rate, and time consuming post-processing. The aim of this first experimental setup for 3D USCT was to analyze the feasibility for breast cancer diagnosis of such a system built with today’s technology and draw conclusions for future setups. The results of this system are presented and discussed in regard of data acquisition, image quality, and duration of image reconstruction. The main conclusion is that 3D USCT is feasible with today’s technology, if a sparse aperture or long DAQ times can be accepted. A setup for a second-generation 3D USCT with the main aim to image volunteers and carry out a small preclinical study is proposed.

关键词： Ultrasonic imaging data acquisition image quality Tomography Acoustic reflection Absorption Acoustic transducers Breast cancer image reconstruction Apertures

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Development of a neonate lung reconstruction algorithm using a wavelet AMG and estimated boundary form

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PHYSIOLOGICAL MEASUREMENT 2008年第6期29卷 S125-S138页

作者： Bayford, R. Kantartzis, P. Tizzard, A. Yerworth, R. Liatsis, P. Demosthenous, A. Middlesex Univ Dept Nat Sci London N17 8HR England City Univ London Sch Engn & Math Sci London EC1V 0HB England UCL Dept Elect & Elect Engn London England

Objective, non-invasive measures of lung maturity and development, oxygen requirements and lung function, suitable for use in small, unsedated infants, are urgently required to define the nature and severity of persisting lung disease, and to identify risk factors for developing chronic lung problems. Disorders of lung growth, maturation and control of breathing are among the most important problems faced by the neonatologists. At present, no system for continuous monitoring of neonate lung function to reduce the risk of chronic lung disease in infancy in intensive care units exists. We are in the process of developing a new integrated electrical impedance tomography (EIT) system based on wearable technology to integrate measures of the boundary diameter from the boundary form for neonates into the reconstruction algorithm. In principle, this approach could provide a reduction of image artefacts in the reconstructed image associated with incorrect boundary form assumptions. In this paper, we investigate the required accuracy of the boundary form that would be suitable to minimize artefacts in the reconstruction for neonate lung function. The number of data points needed to create the required boundary form is automatically determined using genetic algorithms. The approach presented in this paper is to assist quality of the reconstruction using different approximations to the ideal boundary form. We also investigate the use of a wavelet algebraic multi-grid (WAMG) preconditioner to reduce the reconstruction computation requirements. Results are presented that demonstrate a full 3D model is required to minimize artefact in the reconstructed image and the implementation of a WAMG for EIT.

关键词： EIT lung imaging boundary form estimation wavelets AMG

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An evaluation of missing data compensation methods for a PET camera by comparing to no-gap data

An evaluation of missing data compensation methods for a PET...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Hossain Baghaei Hongdi Li Yuxuan Zhang Rocio A. Ramirez Shitao Liu Chao Wang Shaohui An Wai-Hoi Wong University of Texas M.D. Anderson Cancer Center Houston TX USA

We evaluated three methods for filling gaps in PET projection data that may results from gaps between detectors or from defective detectors. These methods include linear interpolation, constraint Fourier space, and forward projection of the images reconstructed from incomplete data iteratively. We compared reconstructed images from the gap-filled data to the images reconstructed from data without gaps acquired by rotating camera gantry during data acquisition. We collected data for a 20-cm flood phantom and the Hoffman brain phantom using the HOTPET camera that has a spatial resolution of about 3 mm. HOTPET Camera has the capability to be rotated during data acquisition and in standard operation it is rotated to fill the gaps in sinograms. images reconstructed from data without gantry rotation and without missing data compensation were dominated by artifacts. Filling the gaps with even the simple and fast linear interpolation resulted in images with significantly less artifacts; however, it was less effective than the other two methods. images from gap-filled data by the other two methods were artifact free but image quality was slightly degraded. Filling the gaps with forward projection of the iterative reconstructed images produced the best results; however, it was the slowest method.

关键词： Positron emission tomography Cameras image reconstruction Filling Detectors Interpolation data acquisition Imaging phantoms Floods Spatial resolution

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Direct 4D list mode parametric reconstruction for PET with a novel EM algorithm

Direct 4D list mode parametric reconstruction for PET with a...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Jianhua Yan Beata Planeta-Wilson Richard E. Carson PET center Yale University New Haven CT USA

We present a direct method for producing images of kinetic parameters from list mode PET data. The time-activity curve for each voxel is described by a one-tissue compartment, 2-parameter model. Extending previous EM algorithms, a new spatiotemporal complete data space was introduced to optimize the maximum likelihood function. This leads to a straightforward parametric image update equation with moderate additional computation requirements compared to the conventional algorithm. Qualitative and quantitative evaluations were performed using 2D (x,t) and 4D (x,y,z,t) simulated list mode data for a brain receptor study. Comparisons with the two-step approach (frame-based reconstruction followed by voxel-by-voxel parameter estimation) show that the proposed method can lead to accurate estimation of the parametric image values with reduced variance, especially for the volume of distribution (v T ).

关键词： Positron emission tomography image reconstruction Kinetic theory Spatiotemporal phenomena Maximum likelihood estimation Equations Performance evaluation Brain modeling Computational modeling Parameter estimation

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Depth computations using data in the form of intensity of pixels for enhanced computer vision

Depth computations using data in the form of intensity of pi...

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International conference on Computing, Communication and Networking, ICCCN

作者： N. Sandyarani v. vaithyanathan Dept. of MCA Dr. MGR University Chennai TN S. India Dept. of CSE SASTRA University Tanjore TN S. India

Literature review on computer vision revealed that considerable work was carried out on making the computer to understand objects and their relative positioning using techniques such as shape from shading etc. No specific references were made on quantitative estimation of depth/depth reconstruction between two points in a given 2D image of a 3D environment. An attempt is made in this paper to address above issue by proposing a second order equation using numerical methods connecting the depth between two points in the given 2D image of a 3D environment and the corresponding difference in pixel intensity values between the same two points in the 2D image. The validity of the proposed equation is verified by comparing with existing methods. The major contribution of the present work is that the depth reconstructed using the proposed equation is in excellent agreement with the corresponding depth using existing methods.

关键词： Computer vision Equations Pixel Humans Object recognition image reconstruction data mining Electrical capacitance tomography Lenses image analysis

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Reference Frame Compression Using Embedded reconstruction Patterns for H.264/AvC Decoder

Reference Frame Compression Using Embedded Reconstruction Pa...

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International conference on Digital Telecommunications (ICDT)

作者： Yuri v. Ivanov David Moloney Software Research Laboratory Movidia Limited Dublin Ireland

This paper presents a novel method of reference frame compression for use in H.264/AvC video codecs. The method comprises a predictive pattern decision for encoding of original 2times2 pixel blocks, selective step quantization and fast reconstruction of embedded patterns during the decoding. The proposed approach has a number of advantages over existing methods, such as random access to compressed data, a constant compression rate of 50% and low cost hardware-friendly implementation requiring less than 7 k gates. Experimental results indicate an acceptable quality loss of 0.47 dB on average for video resolutions from CIF to 720p and only 5-15% increase in total computational complexity for the software implementation.

关键词： Automatic voltage control Decoding image coding video compression Hardware Quantization Costs Computational complexity image reconstruction Transform coding

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Partial scan artifact reduction (PSAR) for the assessment of cardiac perfusion in dynamic phase-correlated CT

Partial scan artifact reduction (PSAR) for the assessment of...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Philip Stenner Bernhard Schmidt Herbert Bruder Thomas Flohr Marc Kachelriess Institute of Medical Physics Erlangen Germany Siemens AG Siemensstr Germany Institute of Medical Physics Henkestr. 91 91052 Erlangen Germany

Cardiac CT achieves its high temporal resolution by lowering the scan range from 2π to π plus *** (partial scan). This, however, introduces CT-value variations depending on the start angle of the π range. These partial scan artifacts are in the order of a few HU and prevent the quantitative evaluation of perfusion measurements. Our PSAR algorithm corrects a dynamic phase-correlated scan without a priori information. In general a full scan does not suffer from partial scan artifacts since all projections in [0; 2π] contribute to the data. In order to maintain the optimum temporal resolution and the phase-correlation PSAR creates an artificial full scan p n F by projection-wise averaging a set of neighboring partial scans p n P from the same perfusion examination (typically N = 30 phase-correlated partial scans distributed over 20 s). Corresponding to the angular range of each partial scan we extract virtual partial scan data sets p n v from the artificial full scan p n F . A standard reconstruction yields the corresponding images f n P , f n F and f n v . Subtracting the artificial full scan image f n F from the virtual partial scan image f n v yields an artifact image that can be used to correct the original partial scan image: f n C = f n P − (f n v − f n F ). Our method has been validated with a simulated semi-anthropomorphic heart phantom and with clinical scans. For the simulated case real full scans have been performed to provide theoretical reference values. The improvement of the root mean square errors between the full scans and the partial, respectively corrected scans, is up to 54%. The phase-correlated data now appear accurate enough for a quantitative analysis of cardiac perfusion.

关键词： Computed tomography Heart Myocardium Spatial resolution image reconstruction Fluctuations Energy resolution Nuclear and plasma sciences Heuristic algorithms data mining

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