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73
Determining Optical Flow
 ARTIFICIAL INTELLIGENCE
, 1981
"... Optical flow cannot be computed locally, since only one independent measurement is available from the image sequence at a point, while the flow velocity has two components. A second constraint is needed. A method for finding the optical flow pattern is presented which assumes that the apparent veloc ..."
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Cited by 2382 (9 self)
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Optical flow cannot be computed locally, since only one independent measurement is available from the image sequence at a point, while the flow velocity has two components. A second constraint is needed. A method for finding the optical flow pattern is presented which assumes that the apparent velocity of the brightness pattern varies smoothly almost everywhere in the image. An iterative implementation is shown which successfully computes the optical flow for a number of synthetic image sequences. The algorithm is robust in that it can handle image sequences that are quantized rather coarsely in space and time. It is also insensitive to quantization of brightness levels and additive noise. Examples are included where the assumption of smoothness is violated at singular points or along lines in the image.
Linear and Cubic Box Splines for the Body Centered Cubic Lattice
 In Proceedings of the IEEE Conference on Visualization
, 2004
"... In this paper we derive piecewise linear and piecewise cubic box spline reconstruction filters for data sampled on the body centered cubic (BCC) lattice. We analytically derive a time domain representation of these reconstruction filters and using the Fourier sliceprojection theorem we derive their ..."
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Cited by 41 (8 self)
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In this paper we derive piecewise linear and piecewise cubic box spline reconstruction filters for data sampled on the body centered cubic (BCC) lattice. We analytically derive a time domain representation of these reconstruction filters and using the Fourier sliceprojection theorem we derive their frequency responses. The quality of these filters, when used in reconstructing BCC sampled volumetric data, is discussed and is demonstrated with a raycaster. Moreover, to demonstrate the superiority of the BCC sampling, the resulting reconstructions are compared with those produced from similar filters applied to data sampled on the Cartesian lattice.
A transformation method for the reconstruction of functions from nonuniformly spaced samples
 IEEE Trans. on Acoustics, Speech, and Signal Processing
, 1985
"... AbstractThe reconstruction of unctions from their samples at nonuniformly distributed locations is an important ask for many applications. This paper presents a sampling theory which extends the uniform sampling theory of Whittaker et ul. [ l l] to include nonuniform sample distributions. This ext ..."
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Cited by 39 (0 self)
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AbstractThe reconstruction of unctions from their samples at nonuniformly distributed locations is an important ask for many applications. This paper presents a sampling theory which extends the uniform sampling theory of Whittaker et ul. [ l l] to include nonuniform sample distributions. This extension is similar to the analysis of Papoulis [15], who considered reconstructions of fnnctions that had been sampled at positions deviating slightly from a uniform sequence. Instead of treating the sample sequence as deviating from a uniform sequence, we show that a more general result can be obtained by treating.the sample sequence as the result of applying a coordinate transformation to the uniform sequence. It is shown that the class of functions reconstructible in this manner generally include nonbandlimited functions. The twodimensional uniform sampling theory of Petersen and Middleton [16] can be similarly extended as is shown in this paper. A practical algorithm for performing reconstructions of twodimensional functions from nonuniformly spaced samples is described, as well as examples illustrating the performance of the algorithm. I.
SPATIOSPECTRAL COLOR FILTER ARRAY DESIGN FOR ENHANCED IMAGE FIDELITY
"... In digital imaging applications, data are typically obtained via a spatial subsampling procedure implemented as a color filter array—a physical construction whereby only a single color representative is measured at each pixel location. Owing to the growing ubiquity of color imaging and display devic ..."
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Cited by 36 (7 self)
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In digital imaging applications, data are typically obtained via a spatial subsampling procedure implemented as a color filter array—a physical construction whereby only a single color representative is measured at each pixel location. Owing to the growing ubiquity of color imaging and display devices, much recent work has focused on the interplay between color filter array design and subsequent digital processing, including in particular the canonical spatiochromatic reconstruction task known as demosaicking. Here we consider the problem of improved color filter array design, leading to enhanced image fidelity. We first analyze the limitations of the wellknown Bayer pattern, currently most popular in industry. We then propose a framework for designing rectangular color filter arrays amenable to efficient and completely linear reconstruction, and provide examples of new patterns that enable improvements in reconstruction quality. Index Terms — Image sensors, color measurement, image sampling, image reconstruction, image color analysis 1.
Practical box splines for reconstruction on the body centered cubic lattice
 IEEE Trans. Vis. Comput. Graphics
, 2008
"... Abstract—We introduce a family of box splines for efficient, accurate, and smooth reconstruction of volumetric data sampled on the bodycentered cubic (BCC) lattice, which is the favorable volumetric sampling pattern due to its optimal spectral sphere packing property. First, we construct a box spli ..."
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Cited by 29 (5 self)
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Abstract—We introduce a family of box splines for efficient, accurate, and smooth reconstruction of volumetric data sampled on the bodycentered cubic (BCC) lattice, which is the favorable volumetric sampling pattern due to its optimal spectral sphere packing property. First, we construct a box spline based on the four principal directions of the BCC lattice that allows for a linear C 0 reconstruction. Then, the design is extended for higher degrees of continuity. We derive the explicit piecewise polynomial representations of the C 0 and C 2 box splines that are useful for practical reconstruction applications. We further demonstrate that approximation in the shiftinvariant space—generated by BCClattice shifts of these box splines—is twice as efficient as using the tensorproduct Bspline solutions on the Cartesian lattice (with comparable smoothness and approximation order and with the same sampling density). Practical evidence is provided demonstrating that the BCC lattice not only is generally a more accurate sampling pattern, but also allows for extremely efficient reconstructions that outperform tensorproduct Cartesian reconstructions. Index Terms—BCC, box splines, discrete/continuous representations, optimal regular sampling. Ç 1
Characterization of Visually Similar Diffuse Diseases from BScan Liver Images Using Nonseparable Wavelet Transform
 Proc. 1997 IEEE Int. Conf. Image Processing
, 1997
"... This paper describes a new approach for texture characterization, based on nonseparable wavelet decomposition, and its application for the discrimination of visually similar diffuse diseases of liver. The proposed featureextraction algorithm applies nonseparable quincunx wavelet transform and uses ..."
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Cited by 22 (1 self)
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This paper describes a new approach for texture characterization, based on nonseparable wavelet decomposition, and its application for the discrimination of visually similar diffuse diseases of liver. The proposed featureextraction algorithm applies nonseparable quincunx wavelet transform and uses energies of the transformed regions to characterize textures. Classification experiments on a set of three different tissue types show that the scale/frequency approach, particularly one based on the nonseparable wavelet transform, could be a reliable method for a texture characterization and analysis of Bscan liver images. Comparison between the quincunx and the traditional wavelet decomposition suggests that the quincunx transform is more appropriate for characterization of noisy data, and practical applications, requiring description with lower rotational sensitivity.
Image Resampling
, 1992
"... This dissertation considers several aspects of the process ..."
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Cited by 21 (4 self)
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This dissertation considers several aspects of the process
Segmentation of Color Images Using a TwoStage SelfOrganizing Network
 Image and Vision Computing
, 2002
"... We propose a twostage hierarchical artificial neural network for the segmentation of color images based on the Kohonen selforganizing map (SAM). The first stage of the network employs a fixedsize twodimensional feature map that captures the dominant colors of an image in an unsupervised mode. Th ..."
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Cited by 16 (2 self)
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We propose a twostage hierarchical artificial neural network for the segmentation of color images based on the Kohonen selforganizing map (SAM). The first stage of the network employs a fixedsize twodimensional feature map that captures the dominant colors of an image in an unsupervised mode. The second stage combines a variablesized onedimensional feature map and color merging to control the number of color clusters that is used for segmentation. A postprocessing noisefiltering stage is applied to improve segmentation quality. Experiments confirm that the selflearning ability, fault tolerance and adaptability of the twostage SaM lead to a good segmentation results. 2002 Elsevier Science B.V. All rights reserved.
A VolumeImaging Radar Wind Profiler for Atmospheric Boundary Layer Turbulence Studies
, 1997
"... This paper describes the turbulent eddy profiler (TEP), a volumeimaging, UHF radar wind profiler designed for clearair measurements in the atmospheric boundary layer on scales comparable to grid cell sizes of large eddy simulation models. TEP employs a large array of antennas—each feeding an indep ..."
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Cited by 14 (4 self)
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This paper describes the turbulent eddy profiler (TEP), a volumeimaging, UHF radar wind profiler designed for clearair measurements in the atmospheric boundary layer on scales comparable to grid cell sizes of large eddy simulation models. TEP employs a large array of antennas—each feeding an independent receiver—to simultaneously generate multiple beams within a 28 � conical volume illuminated by the transmitter. Range gating provides 30m spatial resolution in the vertical dimension. Each volume image is updated every 2–10 s, and long datasets can be gathered to study the evolution of turbulent structure over several hours. A summary of the principles of operation and the design of TEP is provided, including examples of clearair reflectivity and velocity images. 1.
Hexagonal Structure for Intelligent Vision
 Information and Communication Technologies, ICICT
, 2005
"... permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Technology, Sydney's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or ..."
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Cited by 14 (2 self)
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permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Technology, Sydney's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to pubs