Using Multiple Images

In this paper, we proposed a novel corner detection algorithm, based on statistical properties of corners, to detect corners of both polygonal and polyhedral objects. By means of local histogram analysis, we first bilevel the subimage within a circular window, then compute the intensity mean for the bileveled subimage. From the intensity mean we can estimate the corner angle. We then calculate the theoretical position variance from the estimated angle. Comparing the position variance from the bileveled subimage with its theoretical value, we can identify whether or not the pixel at the center of the subimage is a corner. Finally, the corner orientation can be obtained from the position mean.Our algorithm can detect corners of both polygons and polyhedra, even if they appear in an image at the same time. It is superior to conventional detection algorithms that it can detect corners over a large range of angles.

We report the realization of a surface plasmon resonance imaging biosensor potentially capable of dynamically characterizing optical anisotropy by means of polarimetric measurements. Our approach relies on a light beam propagating through a high refractive index glass-prism (Kretschmann-Raether configuration) in order to excite a surface plasmon wave along a metal-dielectric interface. This evanescent wave probes the metal-dielectric vicinities with subnanometer sensitivity, thus resolving optical characteristics of adsorbed biomolecular targets. Fixing wavelength and angle of incidence of the beam enables real-time monitoring of adsorptions and desorptions of targets onto the whole surface of the chip, allowing for example characterization of DNA:DNA interaction kinetics with applications to genetic diagnosis. The polarimetric surface plasmon resonance imaging device uses a pyramid of high index glass and two orthogonal SPR imaging sensor arms. The interface is probed along two orthogonal directions. A signal difference in reflection between the two arms should allow us to resolve local optical anisotropy of the dielectric medium, keeping the parallel and real-time capabilities of the system. Additional information can be obtained by varying the angle of incidence of the light beam or tuning its wavelength. We believe that this type of sensor will be useful for studying collective biomolecular assemblies' conformational changes.

Tensor magnetic hysteresis loop measurements of a steel cube

Auger electron spectroscopy is a versatile tool in studying the chemical constituents of dispersions in rubber. This technique combined with the SAM analyses produces two dimensional images which are useful in the elucidation of aggregations and dispersion states of the rubber additives. Especially, particle inclusions and agglomerations can be studied together with the topographic features of the complementary SED image. Additional information concerning the binding states of elastomers and additives, aggregations of excessive crosslinkages, unsaturated double bonds, and large hard segments of polymers can be imaged with the aid of chemical reactants. The success of the present AES technique depends on the proper preparation of sample surfaces. A conductive surface is an essential factor in the analyses of additive dispersions. The heating of the surface by the electron beam, as well as the alternation of the surface topology by electron specimen interactions, should also be considered in the correct interpretation of the observed images. Artifacts associated with the analysis should be carefully examined so that they might reveal information about the composition and heterogeneity.

Background： Three-dimensional echocardiography has good feasibility and real image display in dynamic and spatial cardiac structures. So we designed this study to assess both the feasibility and potential role of three-dimensional echocardiography for the evaluation of cardiac structures and adjacent relationships. Method：We studied 25 patients with various heart structures. Cross-sectional images of specific interesting region were acquired from multiplane transesophageal echocardiography and reconstructed to three-dimensional images by TomTec image processing system. These images were presented in volume-rendered dynamic display for assessing of additonal informations. Results：Three-dimensional reconstructions of usual viewpoints and interesting cut planes were possible in all patients. When compared with standard two dimensional images, additional informations were provided in all reconstructed cases. Among these images, mitral valve morphology, aortoseptal continuity and interatrial septum were the structures for which three-dimensional echocardiography were most useful. Conclusion：Although it was preliminary datas which needs large-scale randonmized prospective studies, three-dimensional echocardiograpy may be most potent and promising methods in evaluating anatomic and functional assessment of heart structures.

The computer ability to detect human being by computer vision is still being improved both in accuracy or computation time. In low-lighting condition, the detection accuracy is usually low. This research uses additional information, besides RGB channels, namely a depth map that shows objects’ distance relative to the camera. This research integrates Cascade Classifier (CC) to localize the potential object, the Convolutional Neural Network (CNN) technique to identify the human and nonhuman image, and the Kalman filter technique to track human movement. For training and testing purposes, there are two kinds of RGB-D datasets used with different points of view and lighting conditions. Both datasets have been selected to remove images which contain a lot of noises and occlusions so that during the training process it will be more directed. Using these integrated techniques, detection and tracking accuracy reach 77.7%. The impact of using Kalman filter increases computation efficiency by 41%.

Imaging spectrometers are essential instruments for hyperspectral remote sensing systems that capture pupil-plane spectral radiance from a scene and ultimately form it into a hyperspectral data cube for processing, analysis, and information extraction. An imaging spectrometer is an EO/IR system, thus it contains all of the basic imaging system components outlined in the previous chapter, exhibits similar design challenges, and is characterized by some of the same performance metrics. In addition to imaging, however, an imaging spectrometer must also capture radiation spectra for each image pixel with adequate fidelity; this places additional demands on system design and adds another dimension to performance characterization. The primary design challenge is that a hyperspectral data cube is essentially a 3D construct, with two spatial dimensions and one spectral dimension, while FPAs are 2D. Therefore, some means are necessary to capture this additional dimension. Often this is done using the time dimension. Various designs that perform this function in different ways are explored in this chapter and subsequent two chapters. In this chapter, we focus on arguably the most common type, the dispersive imaging spectrometer. Dispersive spectrometers use either a prism or grating to spatially spread a spectrum of incident radiation across a detector array. In a dispersive imaging spectrometer, depicted conceptually in Fig. 7.1, the spectrum is dispersed in one direction, while the image is relayed in an orthogonal direction. In the direction of dispersion, it is necessary to limit the field of view to one spatial element; this is performed using a slit. If the field of view is not thusly limited, irradiance distribution on the detector array will resemble an image with large lateral chromatic aberration. In that way, a back-end spectrometer only captures a single line of the 2D field produced by front-end optics. A scanning mechanism, such as the pushbroom or whiskbroom method discussed in Chapter 6, is required to image from frame to frame in a direction orthogonal to the slit. As this occurs, a hyperspectral data product is formed as a sequence of spatial-spectral frames, as depicted in Fig. 7.2. The composite set forms a hyperspectral data cube.

In this paper we design and construct gradient coils for a Halbach permanent magnet array magnetic resonance (MR) scanner. The target field method, which is widely applied for the case of axial static magnetic fields, has been developed for a transverse static magnetic field as produced by a Halbach permanent magnet array. Using this method, current densities for three gradient directions are obtained and subsequently verified using a commercial magneto-static solver. Stream functions are used to turn the surface current densities into wire patterns for constructing the gradient coils. The measured fields are in good agreement with simulations and their prescribed target fields. Three dimensional images have been acquired using the constructed gradient coils with very low degree of geometric distortion.

Most existing methods for edge detection rely on contrast dependent thresholds. We show that a local measurement defined by the ratio of the smallest to the largest eigenvalue of the second moment matrix of filter kernels, can be used to separate smooth, low curvature curves and straight lines from noise, independent of contrast, in both color and gray level images. This is done without applying a threshold to the gradient magnitude. The edge images are defined as zero crossings in the gradient direction. The covariance matrix can easily be computed for both gray level images and color images. Further we show the potentiality of such a measure by integrating it with the Hough transform to extract long straight lines in noisy color images. The method is shown to successfully extract consistent line features from color images of a scene, captured under drastically different lightening conditions.

Design of a high-performance non-linear gradient coil for diffusion weighted MRI of the breast

The theory of polynomials over finite fields is important for investigating the algebraic structure of finite fields as well as for many applications. Above all, irreducible polynomials—the prime elements of the polynomial ring over a finite field—are indispensable for constructing finite fields and computing with the elements of a finite field. Section 1 introduces the notion of the order of a polynomial. An important fact is the connection between minimal polynomials of primitive elements (so-called primitive polynomials) and polynomials of the highest possible order for a given degree. Results about irreducible polynomials going beyond those discussed in the previous chapters are presented in Section 2. The next section is devoted to constructive aspects of irreducibility and deals also with the problem of calculating the minimal polynomial of an element in an extension field. Certain special types of polynomials are discussed in the last two sections. Linearized polynomials are singled out by the property that all the exponents occurring in them are powers of the characteristic. The remarkable theory of these polynomials enables us, in particular, to give an alternative proof of the normal basis theorem. Binomials and trinomials — that is, two-term and three-term polynomials—form another class of polynomials for which special results of considerable interest can be established. We remark that another useful collection of polynomials— namely, that of cyclotomic polynomials—was already considered in Chapter 2, Section 4, and that some additional information on cyclotomic polynomials is contained in Section 2 of the present chapter.

To achieve the effective navigation of microscale agents in the vascular network, a high magnetic field strength with high directional magnetic gradients are required. So far, the methods that have been investigated support only one of these specifications but not both. Here, we propose a new method dubbed dipole field navigation (DFN) that provides high field strength to bring magnetic agents at saturation magnetization with gradients exceeding 300 mT/m at any depth within the human body. For DFN, the high field strength is achieved by placing the patient in the tunnel of a clinical MRI scanner, while high gradients are generated by the distortions of the scanner's homogeneous field from larger ferromagnetic cores placed at specific locations outside the patient. The main challenge of DFN lies in the methods that are required to adequately place the cores in the tunnel. Here, a first method is presented to solve the inverse magnetic problem of positioning such a set of cores so that microscale agents could be guided through a desired path in the vascular network. As a first proof of concept, magnetic particles were steered successfully in three consecutive bifurcations in a 3-D in vitro network.

Changing the Face of Head and Neck Radiotherapy

Traditional Normarski differential interference contrast (DIC) microscopy is a very powerful method for imaging nonstained biological samples. However, one of its major limitations is the nonquantitative nature of the imaging. To overcome this problem, we developed a quantitative DIC microscopy method based on off-axis sample self-interference. The digital holography algorithm is applied to obtain quantitative phase gradients in orthogonal directions, which leads to a quantitative phase image through a spiral integration of the phase gradients. This method is practically simple to implement on any standard microscope without stringent requirements on polarization optics. Optical sectioning can be obtained through enlarged illumination NA.

4 - Forming textile composites