bluuebunny/crossref_metadata_2025 huggingface dataset:
Invariants under image perspective transformations: Theory and examples
Authors: Barrett Eamon B. , Payton Paul M. , Brill Michael H. , Haag Nils N.
Published: March 2007

The objective of this work is to develop automated techniques for recognizing the same objects in images that differ in scale, tilt, and rotation. Such perspective transformations of images are produced when aerial images of the same scene are taken from different vantage points. The algebraic methods developed previously do not utilize the intensity values of the images, i.e., their pixel gray levels. Since image features essential for object recognition, such as edges and local image textures, may be described in terms of derivatives and integrals of the image intensity, it is necessary to investigate whether certain differential and integral operators applied to different perspective views of the same object are also invariant under the perspective transformation. We proceed to derive new differential operators and their corresponding integral invariants for curves and planar objects. We introduce a variant form of Fourier expansion specially adapted to the projective transformation. Extensions to three dimensions are discussed, as well as applications to other image formation models such as synthetic aperture radar (SAR). These results are steps toward a computational model for perspective‐independent object recognition.
Feature classification techniques in model‐based object recognition
Authors: Acton Scott T. , Bovik Alan C.
Published: March 2007

We describe a system that performs model‐based recognition of the projections of generalized cylinders, and present new results on the final classification of the feature data. Two classification methods are proposed and compared. The first is a Bayesian technique that ranks the object space according to estimated conditional probability distributions. The second technique is a new feed‐forward “neural” implementation that utilizes the back‐propagation learning algorithm. The neural approach yields a 31.8% reduction in classification error for a database of twenty models relative to the Bayesian approach, although it does not provide an ordered ranking of the object space. The accuracy results of the neural approach represent a significant performance advance in feature‐based recognition by perceptual organization without the use of depth information. Examples are provided using the results of a simple segmentation system applied to real image data.
Image motion estimation by clustering
Authors: Bandopadhay Amit , Aloimonos John (Yiannis)
Published: March 2007

Image motion is estimated by matching feature “interest” points in different frames of video image sequences. The matching is based on local similarity of the displacement vectors. Clustering in the displacement vector space is used to determine the set of plausible match vectors. Subsequently, a similarity‐based algorithm performs the actual matching. The feature points are computed using a multiple‐filter image decomposition operator. The algorithm has been tested on synthetic as well as real video images. The novelty of the approach is that it handles multiple motions and performs motion segmentation.
Information contained in the motion field of lines and the cooperation between motion and stereo
Authors: Faugeras Olivier D. , Navab Nassir , Deriche Rachid
Published: March 2007

We investigate the relationships that exist between the three‐dimensional structure and kinematics of a line moving rigidly in space and the two‐dimensional structure and kinematics (motion field) of its image in one or two cameras. We establish the fundamental equations that relate its three‐dimensional motion to its observed image motion. We show how this motion field can be estimated from a line‐based token tracker. We then assume that stereo matches have been established between image segments and show how the estimation of the motion field in the two images can be used to compute part of the kinematic screw of the corresponding 3D line. The equations are linear and if several lines belong to the same object provide a very simple way to estimate the full kinematic screw of that object. Finally, we show how the motion field can constrain the stereo matches by establishing necessary conditions that must be satisfied by the motion field of segments which are images of lines belonging to the same object. Only part of this theory has been implemented yet. This part uses Kalman filtering. Several experimental results using synthetic and real data are presented.
Properties of essential matrices
Authors: Maybank S. J.
Published: March 2007

We use essential matrices to show that if the recovery of camera displacement from image correspondences is unstable, then a small perturbation yields an ambiguous set of correspondences. We show that there are at most three camera displacements compatible with a dense set of correspondences, and we show that the symmetric and the antisymmetric parts of an essential matrix are related.
Comparison of statistical methods in MR imaging
Authors: Godtliebsen Fred , Spjsøtvoll Emil
Published: March 2007

The problem of recovering the true underlying scene from a noisy image is considered. Several methods are compared empirically by applying them to magnetic resonance (MR) images. It turns out that a simple method, the Gaussian window filter, gives good results. This method requires only “instantaneous” processing.
Seismic reverberations and the remote estimation of properties of underwater soils
Authors: McGee T. M.
Published: March 2007

Seismic reflection profiles contain not only primary reflections but also sequences of reverberating events called multiple reflections. Field recordings are presented that demonstrate various types of multiple reflections that commonly occur on marine seismic profiles. Their presence is enhanced by the fact that submarine soils often exhibit so little dip that they approximate horizontal layers. If the recording geometry is such that the seismic wave fronts propagate in a direction perpendicular to the layers, individual wavelets within sequences can be identified on the basis of their record times. Having been identified, the amplitudes and phases of these wavelets can be compared to provide information concerning the material within which they reverberate. The comparison does not rely on knowledge of the source. An example of estimating sea‐floor density by comparing water‐layer multiples is given. Observations in waters that have received industrial effluent indicate that such comparisons could be useful when investigating accumulations of waste material.
The advanced spaceborne thermal emission and reflectance radiometer (Aster)
Authors: Kahle Anne B. , Palluconi Frank D. , Hook Simon J. , Realmuto Vincent J. , Bothwell G.
Published: March 2007

The Advanced Spaceborne Thermal Emission Reflectance Radiometer (ASTER) is the only high‐spatial‐resolution multispectral imager scheduled to fly in Earth orbit on the first platform of NASA's Earth Observation System (EOS‐A). The instrument will nave three bands in the visible near infrared with 15‐m spatial resolution, six bands in the short‐wave infrared with 30‐m spatial resolution and five bands in the thermal infrared with 90‐m spatial resolution. There will be an additional band in the near infrared with 15‐m spatial resolution that will provide same‐orbit stereo data when combined with the corresponding nadir viewing band. The ASTER instrument is being built by the Japanese Government based on the scientific requirements of the ASTER science team. This team consists of Japanese and American scientists, who will also be responsible for the development of algorithms for data reduction and analysis. The ASTER will be able to address a variety of science objectives identified by the EOS global change program. ASTER will provide surface temperatures and emissivity estimates, surface reflected radiances and digital elevation models at a spatial scale that will allow detailed process studies for MODIS and other global monitoring instruments at the subpixel level. Existing aircraft instruments can be used to simulate data that will be provided by ASTER. Examples are shown here of surface temperature mapping, surface compositional mapping, and digital elevation models derived from the NASA Thermal Infrared Multispectral Scanner, the Airborne Visible Infrared Imaging Spectrometer, and aerial photography.
Drawings recognition using two‐dimensional graph grammars
Authors: Matsello V. V.
Published: March 2007

A new formal model for description and recognition of strictly defined sets of line drawing images is proposed. The fast image‐parsing algorithm associated with this model is described and its effectiveness is discussed. The algorithm allows one to obtain a structural description of a drawing picture. Using such a description it is possible to perform both the usual classification and a deep structural analysis of the picture.
Can a computer vision system work like the human one?
Authors: Alexandrov V. V. , Gorsky N. D.
Published: March 2007

Problems of human visual perception simulation in computer vision systems are considered. The role of inner imagery models is discussed. Special attention is paid to the activity of the computer vision system, its self‐development under the influence of environment, and its integration with other subsystems.
Unification scheme for 3D surface reconstruction using physically based models
Authors: Wang Y. F. , Lee Jeng‐Feng , Wang Jih‐Fang
Published: March 2007

We propose a unification framework for three‐dimensional shape reconstruction using physically based models. A variety of 3D shape reconstruction techniques have been developed in the past two decades, such as shape from stereopsis, from shading, from texture gradient, and from structured lighting. However, the lack of a general theory that unifies these shape reconstruction techniques into one framework hinders the effort of a synergistical image interpretation scheme using multiple sensors/information sources. Most shape‐from‐Xtechniques use an “observable” (e.g., the stereo disparity, intensity, or texture gradient) and a model, which is based on specific domain knowledge (e.g., the triangulation principle, reflectance function, or texture distortion equation) to predict the observable, in 3D shape reconstruction. We show that all these “observable–prediction‐model” types of techniques can be incorporated into our framework of energy constraint on a flexible, deformable image frame. In our algorithm, if the observable does not confirm to the predictions obtained using the corresponding model, a large “error” potential results. The error potential gradient forces the flexible image frame to deform in space. The deformation brings the flexible image frame to “wrap” onto the surface of the imaged 3D object. Surface reconstruction is thus achieved through a “package wrapping” or a “shape deformation” process by minimizing the discrepancy in the observable and the model prediction. The dynamics of such a wrapping process are governed by the least action principle which is physically correct. A physically based model is essential in this general shape reconstruction framework because of its capability to recover the desired 3D shape, to provide an animation sequence of the reconstruction, and to include the regularization principle into the theory of surface reconstruction.
Use of fourier and hartley transforms in motion estimation: A comparative study
Authors: Mahmoud Sabri A.
Published: March 2007

A comparison between the use of Fourier and Hartley transforms for motion estimation of multiple moving objects in image sequences is presented. The spectrum of the two transforms show that the temporal frequencies at the peaks (of the spectrum) is related to the velocity of the moving objects. The analysis shows that the Hartley technique is faster and requires less memory space than the Fourier technique. However, it gives the velocity of the moving objects but not the direction. The Fourier spectrum, on the other hand, gives the velocity and direction. An efficient implementation is possible by using the Hartley transform to estimate the temporal frequencies of the peaks and hence the velocities. The fast Fourier transform is then used to compute the spectrum at those peaks. The direction is easily found from the Fourier spectrum by reversing the sign of the temporal frequency corresponding to the peak.
Orthogonal decomposition technique for ionospheric tomography
Authors: Na Helen , Lee Hua
Published: March 2007

The possibility of reconstructing two‐dimensional electron‐density profiles in the ionosphere with ionospheric tomography is significant. However, due to the nature of the imaging system, there are several resolution degradation parameters. In order to compensate for these degradation parameters, a priori information must be used. This article introduces the orthogonal decomposition algorithm for image reconstruction, which uses the a priori information to generate a set of orthogonal basis functions for the source domain. This algorithm consists of two simple steps: orthogonal decomposition and recombination. In the development of the algorithm, it is shown that the degradation parameters of the imaging system result in correlations among projections of orthogonal functions. Gram–Schmidt orthogonalization is used to compensate for these correlations, producing a matrix that measures the degradation of the system. Any set of basis functions can be used, and depending upon this choice, the nature of the algorithm varies greatly. Choosing the basis functions of the source domain to be the Fourier kernels produces an algorithm capable of isolating individual frequency components of individual projections. This particular choice of basis functions also results in an algorithm that strongly resembles the direct Fourier method, but without requiring the use of inverse Fourier transforms.
New human visual system model and its application for designing image transmission systems
Authors: Krasilnikov N. N.
Published: March 2007

The advantage of the new human visual system model consists in its ability to take visual system properties into account more accurately. Because of this, it guarantees close agreement between subjective image impairment assessment on the one hand, and estimations obtained by this model on the other. This fact gives good grounds to exclude the human observer of the iteration process of parameters optimization for television equipment to be developed.
Prototype machine vision system for segmentation of hide images
Authors: Chetverikov Dmitry , Lerch Attila
Published: March 2007

We give a brief description of the operation principles of LeaVis, a prototype industrial machine vision system aimed at processing and segmentation of the images of hides marked by lines and other symbols that show defects and areas of different quality. The goal of LeaVis is to provide a visual input for a CAD system that sets trajectories for the knife cutting the hides. We discuss the basic motivations of the vision system design, present some of its algorithms, and demonstrate examples of their operation.
Stabilization of optical image in earth's surveillance systems
Authors: Bonshtedt B. E. , Eskov D. N. , Smirnov A. J.
Published: March 2007

Videodata processing in electronic digital image stabilization systems has been investigated. Advantages of the new information technique over the traditional electromechanic stabilization is discussed.
Migration and dip‐moveout seismic processes expressed as an invariant two‐dimensional convolution
Authors: Bardan Virgil
Published: March 2007

Migration and dip‐moveout (partial prestack migration) are two‐dimensional (space and time) processes of fundamental importance in digital processing of seismic data. Their goal is to make the seismic section appear similar to the geological image along the seismic line subsurface. In this article we study migration and dip‐movement processes from the point of view of their impulse responses. The constant‐velocity migration process is a space‐invariant and time‐variant operator. We demonstrate and illustrate by examples of synthetic and real seismic sections that by transforming the time axis with a square function the constant‐velocity migration operator becomes temporally stationary as well as spatially stationary, that is, it can be expressed as an invariant two‐dimensional convolution. The dip‐moveout seismic process can be applied to constant‐offset seismic sections or to shot seismic profiles. The application of dip‐moveout process to constant‐offset sections is also a temporally varying and spatially stationary operator. By transforming the time axis with a logarithmic function the constant‐offset dip‐moveout operator becomes temporally stationary as well as spatially stationary. The shot dip‐moveout operator is space variant and time variant. After a logarithmic transformation of both the time and the space coordinates, it becomes time invariant and space invariant. Therefore the dip‐moveout seismic processes can be also expressed as an invariant two‐dimensional convolution. We illustrate this by examples of synthetic seismic sections.
Optimum rigid motion with one perspective view
Authors: Holt Robert J. , Netravali Arun N.
Published: March 2007

One of the central problems in dynamic computer vision is the determination of motion from correspondence of points on the visible surface of a moving object obtained at two different times. In the problem we consider, the initial position of several feature points on some object is assumed to be known. Then at some later time instant the corresponding perspective projection of those points is given. The moving body may be nonrigid or the measurements may be corrupted with noise. In either case, we determine the multiplicity of possible solution for the best‐fitting rigid motion. We show that whenever at least three point correspondences are given, there are at most two possible solutions for the best‐fitting rigid motion if the object space is two‐dimensional, while there are at most forty possible solutions if the object space is three‐dimensional. In the latter case the number of possible solutions drops to four if three point correspondence are known, the body is rigid, and the measurements are noise‐free. Several examples are worked out to illustrate our results.©1994 John Wiley & Sons Inc
Neural network approach to segmentation of magnetic resonance head images
Authors: Oshio Koichi , Singh Manbir
Published: March 2007

A novel image segmentation scheme based on a neural network has been implemented to segment magnetic resonance head images. A three‐layer perceptron‐type neural network, trained with backward error propagation algorithm was used. The scheme utilizes first‐echo intensity and computed T2 values to construct a two‐parameter space for classification. After training on a selected slice, the method successfully segments all slices for a given subject without any further human interaction.
Quantitative NMR spectroscopy by matrix pencil methods
Authors: Wang Yi‐Min , Lee Hua , Apte Dipali V.
Published: March 2007

The matrix pencil (MP) method, based on the singular value decomposition (SVD), is applied to quantitative NMR spectroscopy. Its relationship to other SVD‐based methods is also presented. Simulations and applications are given to demonstrate the capability of superior performance.©1993 John Wiley & Sons Inc
On a Bayesian approach to coherent radar imaging
Authors: Styerwalt David , Heidbreder Glenn R.
Published: March 2007

In coherent imaging the object of interest is complex but only its amplitude is to be estimated. The object phase yields nuisance variables and in a proper Bayesian approach it is necessary to obtain a phaseless likelihood function. We investigate a two‐dimensional case in which the target object is modelled as a collection of point scatterers having independent random phases. The phaseless likelihood function is determined exactly for a configuration of data samples in a uniformly spaced square array in spatial frequency when the target scatterers are confined to lattice positions of a “matched” spatial array. It is determined approximately when the target scatterers are arbitrarily positioned, at most one per conventional resolution cell. The relation between maximum likelihood and conventional Fourier transform imaging is explored and the feasibility of a CLEAN algorithmic technique in coherent imaging is considered.©1993 John Wiley & Sons Inc
An application of splines to maximum likelihood radar imaging
Authors: O'Sullivan Joseph A. , Snyder Donald L. , Porter Donald G. , Moulin Pierre
Published: March 2007

Recent results in radar imaging using estimation theoretic techniques are applied to forming images from data from a compact radar range. Nonparametric maximum likelihood methods based on spline approximations are used. The object imaged is a one meter diameter sphere covered with wrinkled aluminum foil. This rough sphere approximately fits the diffuse model and the ideal scattering function for a rough rotating sphere is known. The results shown demonstrate that the proposed algorithm is realizable and that the image are comparable to simulations.©1993 John Wiley & Sons Inc
Segmentation of SAR images using the wavelet transform
Authors: Du Li‐Jen , Lee Jong‐Sen , Hoppel Karl , Mango Stephen A.
Published: March 2007

Multiresolution representation of images using the wavelet transform is a new approach for the analysis of image information content. The transform can be computed efficiently by a pyramidal algorithm based on convolution with quadrature mirror filters. The result is a set of subband images which consists of a lower resolution version of the original image and a sequence of detail images containing higher frequency spectral information. We used this representation for the supervised segmentation of polarimetric SAR images of the San Francisco Bay area acquired by the airborne JPL system for identifying various terrain covers. Since the wavelet transform generates the localized spatial and spectral information simultaneously, detailed knowledge of the texture variations within an image can be extracted from the data in the spectral subbands. The segmentation algorithm developed in this paper is formulated by taking into consideration both the intensity and the texture information. For polarimetric SAR images, the classification accuracy can be enhanced, if the combined data from copolarized and cross‐polarized images are used in the discrimination process. In contrast to other texture segmentation approaches, this algorithm does not require extensive calculations.©1993 John Wiley & Sons Inc
Inverse scattering of Hz waves using local shape‐function imaging: A T‐matrix formulation
Authors: Otto Gregory P. , Chew Weng Cho
Published: March 2007

Inverse scattering algorithms for Hz polarized waves are scarce, due to the added difficulties of polarization charges. Nevertheless, the polarization charges cannot be ignored for 3D problems as well as for 2D Hz problems. This work aims to reconstruct arbitrary inhomogeneous dielectric objects from Hz scattering data using a new formulation that abandons the standard integral equation model for a T‐matrix model. This new algorithm, called local shape‐function (LSF) imaging, is modified for dielectric objects with Hz incident fields, where previously the LSF algorithm was applied to metallic objects with Ez incident fields. The advantage of the LSF algorithm is a more accurate modeling of the induced interfacial polarization charges. For comparison, the Hz distorted Born iterative method using integral equations is shown to be valid only for small contrasts, while the LSF algorithm converges for much larger dielectric contrasts.©1994 John Wiley & Sons Inc
Frequency‐directivity scanning in laboratory radar imaging
Authors: Bertrand Jacqueline , Bertrand Pierre , Ovarlez Jean‐Philippe
Published: March 2007

This work concerns an extension of usual radar imaging in which the pictures of the target do not simply exhibit the position of elementary reflectors but also give the behavior of these reflectors when the frequency and the direction of illumination vary. Essentially, the technique consists of describing the target by a generalized image which can be computed from the knowledge of the backscattering function on a large domain in the angle‐frequency space. A discussion of the physical relevance of the approach is given and its conclusions are used to derive a practical formulation relying on a special wavelet transform. The implementation of the technique is developed by using the fast Mellin transform. Special features of the method are the use of data in polar format without resampling and the fact that the computation can be easily parallelized.©1994 John Wiley & Sons Inc
Ionospheric tomography algorithms
Authors: Raymund T. D.
Published: March 2007

The relatively recent development of inexpensive, high‐speed computational resources has made computerized tomography a readily accessible tool for remote sensing. A variety of geophysical remote applications have made use of the technique; in particular, tomography has been used to image the electron density in the Earth's ionosphere. As in most cases there are problems unique to the application. A review of the algorithms used to date is presented with a sampling of experimental results.©1994 John Wiley & Sons Inc
Resolution analysis of ionospheric tomography systems
Authors: Na Helen , Sutton Eric
Published: March 2007

One of the most recent applications for tomographic imaging is the measurement of the electron density distribution in the ionosphere. This imaging system is a unique and challenging tomographic system because of the physical constraints of the system and the nature of the electron density distribution. To fully understand the potential and limitations of this imaging system, analysis of the resolving capabilities is needed. This article provides a review of current analysis methods for both system evaluation and characterization of the effects of individual degradation parameters. This article also presents a study of the effect of system configuration on the information content of projections.©1994 John Wiley & Sons Inc
Finite state residual vector quantizer for image coding
Authors: Huang Steve Shih‐Yu , Wang Jia‐Shung
Published: March 2007

Finite state vector quantization (FSVQ) has been proven to be a high‐quality and low‐bit rate coding scheme. An FSVQ has achieved the efficiency of a small codebook (the state codebook) VQ while maintaining the quality of a large codebook (the master codebook) VQ. However, the large master codebook becomes a primary limitation of FSVQ when the implementation is carefully taken into account. A large amount of memory would be required in storing the master codebook, and much effort would be spent in maintaining the state codebook if the master codebook became too large. This problem could be partially solved by the mean/residual technique (MRVQ)‐that is, the block means and the residual vectors would be separately coded. However, MRVQ has its own drawbacks. Additional bits would be required in coding those means. Moreover, electing the state codebooks in the residual domain would be difficult. A new hybrid coding scheme called the finite state residual vector quantization (FSRVQ) is proposed in this article for the sake of using both advantage in FSVQ and MRVQ. The codewords in FSRVQ were designed by removing the block means to reduce the codebook size. The block means were predicted by the neighboring blocks to reduce the bit rate. In addition, the predicted means were added to the residual vectors so that the state codebooks could be generated entirely. The performance of FSRVQ was indicated from the experimental results to be better than that of both ordinary FSVQ and MRVQ uniformly.©1994 John Wiley & Sons Inc
Part segmentation from stereo
Authors: Chen Liang‐Hua , Lin Wei‐Chung , Liao Hong‐Yuan Mark
Published: March 2007

This article addresses the problem of segmenting objects into parts using stereo images. There are three components in the part segmentation process: surface segmentation, region grouping, and volumetric models (superquadrics) recovery/segmentation. The surface segmentation process segments the image into a set of regions such that each region represents a smooth surface. The region grouping process merges the segmented regions into parts. Finally the process of volumetric models recovery/segmentation recovers the part model and segments that part into smaller parts if necessary. Because we use both surface and volumetric models to drive the part segmentation process, we can capture more geometric properties of the object, and the application domain of our approach is broader than that of previous approaches. The performance of the proposed system is demonstrated with real images and synthetic images. Experimental results show that the system is stable and capable of handling a variety of objects.©1994 John Wiley & Sons Inc
Stochastic geophysical diffraction tomography
Authors: Tsihrintzis George A. , Devaney Anthony J.
Published: March 2007

We revisit geophysical diffraction tomography (GDT) and cast it into a stochastic framework, in which the geophysical formation to be imaged is modeled as a realization of a two‐dimensional stationary random process. It is shown that the optimum reconstruction algorithm, in both the cases of offset vertical seismic profiling and well‐to‐well probing, attains a modified filtered backpropagation form.©1994 John Wiley & Sons Inc
Architecture and implementation of the grand alliance HDTV video encoder
Authors: Mailhot John N. , Paik Woo H.
Published: March 2007

A high‐definition television (HDTV) video compression encoder is being constructed for use during the standardization process for United States terrestrial broadcast HDTV. The encoder generates an MPEG‐2 main profile/high level compliant bitstream at compressed data rates from 10–80 million bits/second. Both interlaced and progressive image formats in image sizes up to 1080 lines × 1920 pixels per line are supported.©1994 John Wiley & Sons Inc
HDTV transmission formats and migration path
Authors: Lim Jae S. , Sunshine Lon E.
Published: March 2007

The current proposal for terrestrial broadcasting of HDTV in the United States incorporates a flexible approach toward encoding and transmission. Specifically, the format used to encode an HDTV picture will not be fixed. Instead, a variety of transmission formats will be available, unlike the current (NTSC) system. Furthermore, although a basic set of formats will exist initially, it is possible that this set can change over time, depending on the evolution of relevant technologies. This article will consider various topics related to the current and future transmission formats associated with HDTV systems in the United States. This article discusses the usefulness of allowing multiple transmission formats and describes the formats which will be immediately available for HDTV broadcasting, as agreed upon by the Grand Alliance. The relationship between source formats, transmission formats, and display formats are discussed, with reference to some of the signal processing modules required to convert between formats. Finally, the migration of HDTV to incorporate additional formats is addressed. This report describes a method of achieving this migration in a backward‐compatible manner, so that the basic HDTV receivers will not become obsolete.©1994 John Wiley & Sons Inc
Optimal image formats for advanced television and the NII
Authors: Demos Gary
Published: March 2007

Various high‐definition television (HDTV) and advanced television (ATV) scanning parameter sets have been proposed, including the “Grand Alliance” proposal before the U.S. Federal Communications Commission. However, the American Society of Cinematographers has recommended that the proposed 16:9 aspect ratio should be replaced by a simpler and more pleasing 2:1 aspect ratio. Various proposed and existing formats of interest include 640 × 480, 864 × 648, 1024 × 768, 1152 × 864, and 1280 × 1024 for computer screens, and widescreen formats at or near 2 megapixels. When these formats are analyzed in the context of forming the basis for a suitable hierarchy of scalable resolutions and temporal rates with this new aspect ratio in mind, some significant patterns emerge. Certain fundamental issues in constructing a convenient hierarchy include progressive scanning (no interlace), square pixels (or simple squeezes), and a simple fractional relationship between members of the hierarchy, both temporally and in resolution. There is also a need to exceed 70 Hz in display rate for the wide, bright screens of HDTV/ATV. There is great value in compatibility with computer displays, which exceed 70 Hz with various common resolutions in today's ubiquitous 4:3 aspect ratio. The development of a national and global information infrastructure (NIL/GII) would benefit greatly from such commonality of computer and HDTV/ATV formats. There will be a need for every display to present the richest possible image quality in support of the presentation of text, graphics, and still images, as well as our national and world hertage of high‐resolution films. It will also be necessary to develop guidelines for the composition of images and text by taking into account the common display formats which will be available. This is done by understanding the common “safe area” throughout the variety of existing and future displays, and by considering legibility on each. The best possible architecture for digital HDTV/ATV for the United States and internationally will be needed to support the major NII/GII applications, including health care, library access, education, collaborative and remote work, interactive news, on‐line commerce, and many other uses in addition to entertainment..©1994 John Wiley & Sons Inc
Imaging in three‐dimensional conformal radiation therapy
Authors: Mohan Radhe , Rothenberg Lawrence , Reinstien Lawrence , Ling C. Clifton
Published: March 2007

By and large, radiation therapy is a noninvasive method of the treatment of cancer requiring knowledge of the precise location and extent of the disease to be destroyed and the organs to be protected from radiation damage. Images have always played a central role in providing the requisite information for this mode of cancer treatment. Different types of images, such as computed tomography (CT); magnetic resonance imaging (MRI), positron emission tomographic (PET), simulator, etc., are used to varying degrees depending upon their relevance to radiation oncology as well as their accessibility. It is often necessary to merge data from various types of images. The availability of three‐dimensional information from tomographic images has allowed the introduction of three‐dimensional conformal radiation therapy (3DCRT) methods. Images are employed for diagnosing and establishing the extent of the disease, planning and delivery treatments, and evaluating the effectiveness of the treatment in controlling the disease and assessing the damage to normal tissues. Each image type has a unique informational content of importance to radiation oncology. To extract the maximum information from images, it is necessary to employ various image processing tools. These tools allow us to perform such functions as (1) image enhancement; (2) image correlation to register information from various images; (3) segmentation of images to extract the surface outlines of the tumor volume and normal anatomic structures; and (4) two‐ and three dimensional data visualization. One important aspect of planning radiation treatments is the computation of dose distribution in the patient for a proposed configuration of radiation beams. This step requires tracing rays in a three‐dimensional CT image data set to compute radiologic path lengths through the patient's body. Although images are employed to a great advantage in radiation oncology, many problems still remain to be solved. Of the various 3DCRT tasks, the outlining of contours of the volume of intended treatment and normal anatomy on images is highly labor‐intensive and fraught with uncertainty. In addition, the integration of data from various imaging modalities is difficult and error prone because of distortions inherent in imaging and also because of the motion, deformation, and displacement of patients and their internal anatomy. Investigations are in progress to find solutions to these problems.
Tomotherapy: Optimized planning and delivery of radiation therapy
Authors: Mackie T. Rockwell , Holmes Timothy W. , Reckwerdt Paul J. , Yang James
Published: March 2007

In contemporary radiotherapy dose optimization, radiation beams and beam modifiers are iteratively selected until the dose distribution is acceptable. Another approach, referred to as the “inverse problem,” is: Given the dose prescription, compute the optimal set of photon beams while preventing unphysical solutions such as negative beam weights, and iterate to achieve the prescription as closely as possible. This solution to this inverse problem, which uses image reconstruction mathematics, entails the delivery of large numbers of nonuniform beam intensities to produce uniform dose distributions. These dose distributions can be arranged to conform very closely to even complex target volumes, yet spare surrounding sensitive tissue. Alternatively, the dose distributions can be arranged to generously treat a regional field and “conformally avoid” overtreating sensitive volumes within the field. Multiple dose prescriptions can be delivered without additional effort. We propose that a practical way of delivering optimized dose distributions would be to intensity modulate a photon beam, using collimator leaves intersecting a slit field of radiation. Modulation is achieved by varying the time that the leaves are blocking the field. A practical geometry to deliver such a beam is a computed tomography‐like gantry configuration, which also lends itself to tomographic setup verification of dose delivered to the patient. We refer to such a delivery method as “tomotherapy.” Several types of tomotherapy simulations have been conducted. A fully three dimensional optimized treatment planning system using iterative filtered back‐projection have been developed. We will present examples of conformal plans for breast and prostate radiotherapy. We have constructed an experimental apparatus for simulating helical tomotherapy delivery by simultaneously rotating and longitudinally translating a phantom past an intensity‐modulated fan beam. A comparison between a computation and and experimentally realized plan is presented. A Monte Carlo simulation of the angular distribution and energy fluence spectrum of 10‐MV photons produced by a tungsten target have been used to estimate the optimized shape and mass of a primary shielding required to meet regulatory standards.
The exponential radon transform and projection filtering in radiotherapy planning
Authors: Bortfeld Thomas R. , Boyer Arthur L.
Published: March 2007

The mathematical problem of generating a desired dose distribution in a patient who has to undergo external beam radiotherapy is closely related to the problem of reconstructing an image from its projections. Under some simplifying assumptions the theory of the exponential Radon transform as developed for SPECT image reconstruction can be successfully applied to the field of radiotherapy. This results in a projection‐filtering algorithm for the calculation of optimal beam profiles. The method yields analytical solutions for circular and triangular dose distributions, and combinations thereof. Practical solutions for arbitrary cases can be found numerically. The problem of unphysical negative values in the calculated beam profiles is solved by a method combining “cutting off” and “shifting”.
A general optimization procedure for stereotactic small‐beam multi‐isocentric radiotherapy
Authors: Lefkopoulos D. , Levrier M. , Bendada S. , Touboul E.
Published: March 2007

Clinical experience in single‐dose stereotactic radiotherapy of irregular complex lesions has shown that new developments in optimization procedures were necessary to improve dose distribution, making this conformal technique more efficient. We propose a conformal procedure for stereotactic radiotherapy of complex lesions treated with multiple isocenters based on the associated targets methodology. The successive steps of this conformal procedure are: (a) the determination of the number of subvolumes; (b) the choice of collimator diameters using a dosimetric data basis; (c) the search by the inverse SVD optimizer algorithm for the optimal irradiation space and the minibeam weights for each subvolume using singular value decomposition; (d) the basis of quantitative evaluation criteria for the choice of satisfactory solutions on dose‐volume histograms and clinical considerations. The efficiency of the SVD optimizer to planify multi‐isocentric treatments was examined in the case of an irregular lesion planified with two isocenters. The condition number of this dual isocentric configuration showed a more ill‐conditioned problem than in the monoisocentric case. Examining different reconstructed weighting vectors, we observed that optimal solutions are obtained with the first singular components and an important healthy tissue overdosage occurs when the number of singular components used in the SVD expansion increases. Our SVD optimization approach is a general procedure which can be applied to different radiotherapy techniques.
Bayesian image restoration in astronomy: Application to images of the recent collision of comet shoemaker‐levy 9 with jupiter
Authors: Molina R. , Mateos J. , Abad J. , De La Blanca N. PÉRez , Molina A. , Moreno F.
Published: March 2007

In this work, we examine simple to complex methods proposed within the Bayesian paradigm to perform image restoration in astronomy. We start by describing the classical conditional and simultaneous autoregressions, then we move on to study how to incorporate smoothness constraints to the classical Richardson‐Lucy restoration method and also how to modify the image scale and define prior models on other scales than the linear one. Finally, we compare those models on images of Jupiter after the impacts of the fragments of the comet Shoemaker‐Levy 9 at two wavelengths.
Palmitic acid substitution on cationic polymers for effective delivery of plasmid DNA to bone marrow stromal cells
Authors: Incani Vanessa , Tunis Emily , Clements Basak Acan , Olson Cori , Kucharski Cezary , Lavasanifar Afsaneh , Uludag Hasan
Published: March 2007

Nonviral gene carriers are actively explored in gene therapy due to safety concerns of the viral carriers. To design effective gene carriers for modification of bone marrow stromal cells (BMSC), an important cell phenotype for clinical application of gene therapy, cationic polymers polyethyleneimine (PEI), and poly‐L‐Lysine (PLL) were substituted with palmitic acid (PA) via amide linkages. Depending on the reaction conditions, PEI and PLL was substituted with 2.2–5.2 and 13.4–16.2 PA per polymer chain. The PA substituted polymers displayed slightly lower binding efficiency towards a plasmid containing Enhanced Green Fluorescent Protein (pEGFP) in an agarose gel binding assay. The cell binding of PLL‐PA, but not PEI‐PA, was particularly enhanced, resulting in higher percentage of the cells displaying a significant polymer uptake. pEGFP delivery into the BMSC was also significantly increased with the PLL‐PA (vs. PLL), but not PEI‐PA (vs. PEI). The transfection efficiency of PLL‐PA was significantly higher (∼fivefold) than the unmodified polymer. We conclude that PA substitution on PLL provides an effective carrier for transfection of primary cells derived from the bone marrow. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007.
Identification of a monopartite sequence in PU.1 essential for nuclear import, DNA‐binding and transcription of myeloid‐specific genes
Authors: Kwok Juliana C. , Perdomo José , Chong Beng H.
Published: March 2007

The Ets transcription factor PU.1 is an essential regulator of normal hematopoiesis, especially within the myeloid lineage. As such, endogenous PU.1 predominantly localizes to the nucleus of mammalian cells to facilitate gene regulation. However, to date, little is known regarding the mechanisms of PU.1 nuclear transport. We found, using HeLa and RAW 264.7 macrophage cells, that PU.1 enters the nucleus via passive diffusion and active transport. The latter can be facilitated by: (i) the classical pathway requiring importin α and β; (ii) the non‐classical pathway requiring only importin β; or (iii) direct interaction with nucleoporins. A group of six positively charged lysine or arginine residues within the Ets DNA‐binding domain was determined to be crucial in active nuclear import. These residues directly interact with importin β to facilitate a predominantly non‐classical import pathway. Furthermore, luciferase reporter assays demonstrated that these same six amino acids are crucial for PU.1‐mediated transcriptional activation of myeloid‐specific genes. Indeed, these residues may represent a consensus sequence vital for nuclear import, DNA‐binding and transcriptional activity of Ets family members. By identifying and characterizing the mechanisms of PU.1 nuclear import and the specific amino acids involved, this report may provide insights into the molecular basis of diseases. J. Cell. Biochem. 101: 1456–1474, 2007. © 2007 Wiley‐Liss, Inc.
Homogeneous enzyme immunoassay for macromolecular antigens using avidin biotin enzyme
Authors: Ashihara Yoshihiro , Nishizono Isao , Miyagawa Eiich , Kasahara Yasushi
Published: March 2007

A unique homogeneous enzyme immunoassay used for the determination of haptens and macromolecular antigens has been developed. It consists of avidin–antigen conjugate, anti‐ligand antibody, and biotin enzyme (propionyl‐CoA carboxylase). The immunological reaction of the conjugate with antibodies specific to ligand sterically prevents enzyme inactivation by avidin. Goat IgG and theophylline were used as model antigens. Avidin–theophylline conjugate inhibited 100% of enzyme activity. Avidin goat IgG conjugate inhibited 90% of enzyme activity.

In this method, the measurable range of theophylline was from 500 ng/ml to 50 μg/ml, and for goat IgG, it was 1–1000 μg/ml.
Hela marker chromosomes in human breast tumors: Proposal about the origin of the hela cell line
Authors: Krizman David B. , Carpenter Nancy J. , Pathak Sen , Olivé Matilde , Cailleau Relda , Hsu T. C.
Published: March 2007

Previous cytogenetic studies have shown that marker chromosomes thought to be unique to the human carcinoma cell line HeLa exist in some human breast tumors, but these studies have not found such markers in human cervical carcinoma lines. The present investigation presents cytogenetic data on 10 breast carcinoma and adenocarcinoma samples taken from fresh solid tumors, pleural effusions, and cell lines established from pleural aspirates. G‐banding analysis showed that 10 of the 19 breast tumor samples studied exhibited one or more HeLa markers. The data have led us to believe that HeLa marker chromosomes are characteristic for human breast adenocarcinomas and infiltrating ductal carcinomas and that the origin of the HeLa line could have been a breast tumor metastatic to the cervix.