Fast digital image stabilization algorithm based on polar transform and circular block matching

This paper proposes a novel approach of selective omission for streets based on mesh density. For meshes with density over threshold, the largest density meshes are taken out by turns and one road segment of them is eliminated. Meanwhile the taken mesh is merged with the adjacent mesh at a time. Road segment to be eliminated is the most unimportant in all segments on the boundary of this mesh according to the parameters reflecting the importance of road segments. In this study, for the different type meshes, their thresholds are different, which can preserve the density difference. The process of eliminating road segments and merging meshes would ensure the network connectivity. This proposed approach considers topological, geometric and semantic properties of the street network. A street network is selectively eliminated employing this approach, and the results of selection achieve better effects.

In HEVC, the structure of coding unit (CU) and prediction unit (PU) is defined, which brings about higher coding efficiency than H.264/AVC. However, the rate distortion (RD) cost calculations of all depths of CUs and partition modes have yielded tremendous coding computational complexity. In order to reduce the complexity, a fast inter-prediction algorithm is proposed based on temporal and spatial correlations in this paper. In the proposed algorithm, the optimal partition mode in HEVC is selected based on its occurrence probability among all the partition modes and the similarity of the CU segmentation and partition mode between two adjacent frames is counted. Based on the optimal mode and similarity of CU segmentation and partition mode, at most two partition modes are evaluated for each CU to save computational complexity. In addition, the spatial correlation of CU segmentation and partition mode between the corresponding located (co-located) CU and its four surrounding CUs are analyzed. Based on this spatial correlation, only the optimal partition mode is evaluated to save the computational complexity for the deeper depths of CUs of the current CU. Simulation results show that the proposed algorithm achieves 65 % coding time reduction with negligible loss in coding efficiency and peak signal-to-noise ratio (PSNR), compared to previous fast mode decision algorithm.

This paper addresses two problems commonly associated with video target tracking system. First, video target detection and tracking usually require extensive searching in a large space to find the best matches for preregistered templates. Existing fast search methods cannot guarantee a global optimal match, which results in substandard performance. To obtain a true global match, a full search at the pixel or sub-pixel level is required. Obviously, this introduces significant computational overhead, which limits the implementation of these algorithms in real-time applications. In this paper, we propose a fast method to compute two-dimensional normalized cross-correlations to efficiently find the global optimal match result from a large image area. Comparisons and complexity analysis are provided to show the efficiency of the proposed algorithm. Second, another challenge commonly faced by detection and tracking systems is the accurate detection of target orientation in a twodimensional image. This problem is motivated by applications where the walk-in and walk-out people need to be detected and a fast image registration method is needed to compensate the change in rotation, translation and size, which is natural since the target's distance from the camera is changing dramatically. To address this issue, we propose a novel and efficient eigenvector-based method to detect target orientation and apply it into automatic human recognition system. Experimental and real-world test results verify that the proposed fast algorithm achieves similar accuracy as the recursive registration method which is computationally expensive.

In this paper, a fast three-dimensional wavenumber scaling algorithm (3-D WSA) was proposed to reconstruct the wideband terahertz (THz) holographic image under the illumination of THz Gaussian beams. By taking the cross-range range coupling term into account, which is usually neglected in some fast algorithm, such as the enhanced phase shift migration (EPSM), the focusing depth for image reconstruction is greatly improved in the proposed fast algorithm. To deal with the cross-range range coupling term, a wavenumber scaling operator (WSO) was developed in the proposed algorithm which only uses chirp multiplications and FFTs with high computation efficiency and free of interpolation. Theoretical analysis on the relationship of the WSO parameters to the resulted maximum non-ambiguous range in holography image reconstruction was carried out with a quantitative criterion derived to appropriately determine the WSO parameters. Simulation results validate the proposed focusing algorithm and indicate that 3D WSA offers almost the same focusing capabilities as the most rigid phase shift migration (PSM) algorithm, meanwhile with computation efficiency greatly improved. Proof-of-principle experiments in 0.2 THz band were also performed based on a monostatic prototype imager. The experimental results demonstrate the effectiveness and the efficiency of the 3D WSA proposed in this paper.

This paper presents a fast image sequence stabilization system that uses one bit transform (IBT) matching based global motion estimation and Kalman filtering based global motion correction. In order to facilitate a fast motion estimation process, image frames are initially converted into a single bit-plane representation using the IBT, and then motion vectors are evaluated matching the IBTs of two consecutive frames using Boolean operations. Because a binary representation is established, the computational complexity of motion estimation is significantly reduced providing a proportionate reduction in power consumption of custom hardware. The global motion vector is computed using local motion vectors of sub-image blocks to further increase the motion estimation speed. For the motion correction part, global motion vectors are accumulated to yield absolute frame displacements and Kalman filtering is employed to achieve stabilization.

Elbow and shoulder kinetics for 26 highly skilled, healthy adult pitchers were calculated using high-speed motion analysis. Two critical instants were 1) shortly before the arm reached maximum external rotation, when 67 N-m of shoulder internal rotation torque and 64 N-m of elbow varus torque were generated, and 2) shortly after ball release, when 1090 N of shoulder compressive force was produced. Inability to generate sufficient elbow varus torque may result in medial tension, lateral compression, or posteromedial impingement injury. At the glenohumeral joint, compressive force, joint laxity, and 380 N of anterior force during arm cocking can lead to anterior glenoid labral tear. Rapid internal rotation in combination with these forces can produce a grinding injury factor on the labrum. After ball release, 400 N of posterior force, 1090 N of compressive force, and 97 N-m of horizontal abduction torque are generated at the shoulder; contribution of rotator cuff muscles in generating these loads may result in cuff tensile failure. Horizontal adduction, internal rotation, and superior translation of the abducted humerus may cause subacromial impingement. Tension in the biceps tendon, due to muscle contraction for both elbow flexion torque and shoulder compressive force, may tear the anterosuperior labrum.

Paleomagnetism of the Zambales ophiolite, Luzon, northern Philippines

Modeling has become indespensable tool for chemically amplified resist (CAR) evaluations. It has been used extensively to study acid diffusion and its effects on resist image formation. Several commercial and academic simulators have been developed for CAR process simulation. For commercial simulators such as PROLITH (Finle Technologies) and Solid-C (Sigma-C), the user is allowed to choose between an empirical model or a concentration dependant diffusion model. The empirical model is faster but not very accurate for 2-dimension resist simulations. In this case there is a trade off between the speed of the simulator and the accuracy of the results. An academic simulator such as STORM (U.C. Berkeley) gives the user a choice of different algorithms including Fast Imaging 2nd order finite difference algorithm and Moving Boundary finite element algorithm. A user interested in simulating the volume shrinkage and polymer stress effects during post exposure bake will need the Moving Boundary algorithm whereas a user interested in the latent image formation without polymer deformations will find the Fast Imaging algorithm more appropriate. The Fast Imaging algorithm is generally faster and requires less computer memory. This choice of algorithm presents a trade off between speed and level of detail in resist profile prediction. This paper surveys the different models and simulator algorithms available in the literature. Contributions in the field of CAR modeling including contributions to characterization of CAR exposure and post exposure bake (PEB) processes for different resist systems. Several numerical algorithms and their performances will also be discussed in this paper.

The downstroke-to-upstroke transition of many insects is characterized by rapid wing rotation. The aerodynamic consequences of these rapid changes in angle of attack have been investigated using a mechanical model dynamically scaled to the Reynolds number appropriate for the flight of small insects such as Drosophila. Several kinematic parameters of the wing flip were examined, including the speed and axis of rotation, as well as the duration and angle of attack during the wing stroke preceding rotation. Alteration of these kinematic parameters altered force generation during the subsequent stroke in a variety of ways. 1. When the rotational axis was close to the trailing edge, the model wing could capture vorticity generated during rotation and greatly increase aerodynamic performance. This vortex capture was most clearly manifested by the generation of lift at an angle of attack of 0°. Lift at a 0° angle of attack was also generated following rotation about the leading edge, but only if the downstroke angle was large enough to generate a von Karman street. The lift may be due to an alteration in the effective angle of attack caused by the inter-vortex stream in the downstroke wake. 2. The maximum lift attained (over all angles of attack) was substantially elevated if the wing translated backwards through a wake generated by the previous stroke. Transient lift coefficient values of nearly 4 were obtained when the wing translated back through a von Karman street generated at a 76.5° angle of attack. This effect might also be explained by the influence of the inter-vortex stream, which contributes a small component to fluid velocity in the direction of translation. 3. The growth of lift with angle of attack was significantly elevated following a 7.5 chord stroke with a 76.5° angle of attack, although it was relatively constant under all other kinematic conditions. 4. The results also indicate the discrepancies between transient and time-averaged measures of performance that arise when unsteady mechanisms are responsible for force generation. Although the influence of wing rotation was strong during the first few chords of translation, averaging the performance over as little as 6.5 chords of motion greatly attenuated the effects of rotation. 5. Together, these modeling results suggest that the unsteady mechanisms generated by simple wing flips could provide an important source for the production of aerodynamic forces in insect flight. Furthermore, the extreme sensitivity to small variations in almost all kinematic parameters could provide a foundation for understanding the aerodynamic mechanisms underlying active flight control.

The controller transfer function and its digital implementation algorithm are derived by transforming a mass-spring layered structure into an equivalent uniform beam, whose wave propagation times among the boundaries, sensor and actuator positions are equal to those of the original mass-spring layered structure. When the actuator is at the top layer, the control can be determined only by the dead time rule. When the actuator is not at the top layer, the control is determined by the dead time rule and the convolution rule. The latter is transformed to the new fast algorithm in order to reduce the computation time since the controller impulse response function to be convoluted with the sensor output has no damping and the convolution integration range cannot be truncated. Time response analysis shows that by the present control, response can be reduced considerably without causing instability.

Fast Collision-Free Motion Planning for Robots by Using Direct Kinematic Solutions

In this paper, a fast watershed-based image segmentation algorithm is proposed. Firstly, a homogeneity gradient image named after H-image is produced, and then the traditional watershed segmentation is used to initially segment the H-image to produce over-segmented image regions (objects), and at last local optimum merging strategy is utilized to merge neighbor regions to construct a hierarchical network of image objects according to different scales. Textural, color and shape information of segments is utilized in the merging process. Experiments demonstrate the validity of the algorithm proposed in this paper.

This paper considers the three-dimensional (3-D) imaging problem for a rotorcraft-borne forward-looking multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) system. The conventional imaging methods, such as the back-projection (BP) algorithm, are computationally expensive, due to the large amount of data obtained from the two-dimensional (2-D) synthetic aperture. To address this problem, we introduce a two-step fast hybrid imaging algorithm, referred to as FHybrid, to enhance the computational efficiency of the conventional BP algorithm for 3-D MIMO SAR imaging. The proposed fast hybrid imaging algorithm combines the efficient pseudo-polar format imaging approach with the classical BP method. We also develop a relaxation-based imaging algorithm, referred to 3DRELAX for the 3-D forward-looking MIMO SAR imaging. FHybrid is used in the 3DRELAX iterations to improve the computational efficiency of 3DRELAX. The effectiveness and efficiency of the proposed imaging algorithms are demonstrated by using several numerical examples of targets at various ranges.

Target shape estimation with UWB pulse radars is a promising imaging technique for household robots. We have already proposed a fast imaging algorithm, SEABED, that is based on a reversible transform BST (Boundary Scattering Transform) between the received signals and the target shape. However, the target image obtained by SEABED deteriorates in a noisy environment because it utilizes a derivative of received data. In this paper, we propose a robust imaging method with an envelope of circles. We clarify by numerical simulation that the proposed method can realize a level of robust and fast imaging that cannot be achieved by the original SEABED.

In this paper, we present a method for digital image stabilization based on Fourier-Mellin transform and phase correlation. We acquire the rotating angle and scaling factor firstly by phase correlation between Fourier-Mellin transform images of the reference and observed images. After rotating and scaling the observed image, implement the phase correlation again to compute the spacial translation. Because of spectral periodicity, the correlation between Fourier-Mellin transform images will be weaken and maybe lead to wrong result when the rotating angle is close to 90°. So we add a coarse search before phase correlation to avoid this situation. And we use a smooth window to reduce the noise in phase correlation. Furthermore, a coordinate mapping chart is recommended to avoid the unnecessary computation cost during creating log-polar image. The experiment results show the proposed method can acquire accurate motion parameters between two adjacent frames.