• License plate localization based on statistical measures of license plate features

      Boonsim, Noppakun; Prakoonwit, Simant; University of Bedfordshire (Association of Computer Electronics and Electrical Engineers, 2014-01)
      — License plate localization is considered as the most important part of license plate recognition system. The high accuracy rate of license plate recognition is depended on the ability of license plate detection. This paper presents a novel method for license plate localization bases on license plate features. This proposed method consists of two main processes. First, candidate regions extraction step, Sobel operator is applied to obtain vertical edges and then potential candidate regions are extracted by deploying mathematical morphology operations [5]. Last, license plate verification step, this step employs the standard deviation of license plate features to confirm license plate position. The experimental results show that the proposed method can achieve high quality license plate localization results with high accuracy rate of 98.26 %.
    • Light field geometry of a standard plenoptic camera

      Hahne, Christopher; Aggoun, Amar; Haxha, Shyqyri; Velisavljević, Vladan; Fernández, Juan Carlos Jácome; University of Bedfordshire (OSA, 2014)
      The Standard Plenoptic Camera (SPC) is an innovation in photography allowing for acquiring two-dimensional images focused at different depths, from a single exposure. Contrary to conventional cameras, the SPC consists of a micro lens array and a main lens projecting virtual lenses into object space. For the first time, the present research provides an approach to estimate the distance and depth of refocused images extracted from captures obtained by an SPC. Furthermore, estimates for the position and baseline of virtual lenses which correspond to an equivalent camera array are derived. On the basis of paraxial approximation, a ray tracing model employing linear equations has been developed and implemented using Matlab. The optics simulation tool Zemax is utilized for validation purposes. By designing a realistic SPC, experiments demonstrate that a predicted image refocusing distance at 3.5 m deviates by less than 11% from the simulation in Zemax, whereas baseline estimations indicate no significant difference. Applying the proposed methodology will enable an alternative to the traditional depth map acquisition by disparity analysis.
    • Low cost estimation of IQ imbalance for direct conversion transmitters

      Li, Wei; Zhang, Yue; Huang, Li-Ke; Cosmas, John; Maple, Carsten; Xiong, Jian; University of Bedfordshire (IEEE, 2014-06)
      A low cost frequency-dependent (FD) I/Q imbalance self-compensation scheme is investigated in this paper. The direct conversion transmitters are widely used in wireless systems. However, the unwanted image-frequencies and distortions are inevitably introduced into the direct conversion system. This problem is even severer in wideband systems. Therefore, the accurate estimation and compensation of I/Q imbalance is crucial. The current compensation method is based on external instruments or internal feedback path which introduces additional impairments and is expensive. This paper proposes a low cost FD I/Q imbalance self-IQ-demodulation based compensation scheme without using external calibration instruments. First, the impairments of baseband and RF components are investigated. Further, I/Q imbalance model is developed. Then, the proposed a self-IQ-demodulation based compensation scheme is investigated. The overall FD I/Q imbalance parameters are estimated by developing a self-IQ-demodulation algorithm. To realize this self-IQ-demodulation algorithm, this paper introduces minor modifications to the current power detector circuit and specially designed training signal. Afterwards, the estimated parameters are applied to the baseband equivalent compensator. This sophisticated algorithm guarantees low computation complexity and low cost. The compensation performance is evaluated in laboratory measurement
    • Multi-layer depth peeling by single-pass rasterisation for faster isosurface raytracing on GPUs

      Liu, Baoquan; Clapworthy, Gordon J.; Dong, Feng (Blackwell Publishing, 2010-06)
    • Multi-layer depth peeling via fragment sort

      Liu, Baoquan; Wei, Li-Yi; Xu, Ying-Qing; Wu, Enhua (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2009)
    • Multi-scale blind motion deblurring using local minimum

      Wang, Chao; Sun, Li-Feng; Chen, ZhuoYuan; Zhang, JianWei; Yang, ShiQiang; Tsinghua University; Hamburg University (Institute of Physics, 2010-01)
      Blind deconvolution, a chronic inverse problem, is the recovery of the latent sharp image from a blurred one when the blur kernel is unknown. Recent algorithms based on the MAP approach encounter failures since the global minimum of the negative MAP scores really favors the blurry image. The goal of this paper is to demonstrate that the sharp image can be obtained from the local minimum by using the MAP approach. We first propose a cross-scale constraint to make the sharp image correspond to a good local minimum. Then the cross-scale initialization, iterative likelihood update and the iterative residual deconvolution are adopted to trap the MAP approach in the desired local minimum. These techniques result in our cross-scale blind deconvolution approach which constrains the solution from coarse to fine. We test our approach on the standard dataset and many other challenging images. The experimental results suggest that our approach outperforms all existing alternatives.
    • Multimodal fusion of biomedical data at different temporal and dimensional scales

      Viceconti, Marco; Clapworthy, Gordon J.; Testi, Debora; Taddei, Fulvia; McFarlane, Nigel J.B. (ELSEVIER IRELAND LTD, 2011-06)
    • Non-linear beam tracing on a GPU

      Liu, Baoquan; Wei, Li-Yi; Yang, Xu; Ma, Chongyang; Xu, Ying-Qing; Guo, Baining; Wu, Enhua (Blackwell Publishing, 2011-12)
    • Novel moving target search algorithms for computer gaming

      Loh, Peter K. K.; Prakash, Edmond C. (Association for Computing Machinery (ACM), 2009-06)
    • Numerical modeling of inhaled charged aerosol deposition in human airways

      Koolpiruck, Diew; Prakoonwit, Simant; Balachandran, Wamadeva (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2004)
    • Object-based three-dimensional X-ray imaging

      Benjamin, Ralph; Prakoonwit, Simant; Matalas, I.; Kitney, R.I.; Imperial College of Science, Technology and Medicine (Kluwer Academic Publishers, 1996-11)
      A form of three-dimensional X-ray imaging, called Object 3-D, is introduced, where the relevant subject material is represented as discrete 'objects'. The surface of each object is derived accurately from the projections of its outline, and of its other discontinuities, in about ten conventional X-ray views, distributed in solid angle. This technique is suitable for many applications, and permits dramatic savings in radiation exposure and in data acquisition and manipulation. It is well matched to user-friendly interactive displays.
    • Occluded feature exploration for direct volume rendering

      Zhou, Zhiguang; Tao, Yubo; Lin, Hai; Dong, Feng; Clapworthy, Gordon J. (2012)
    • Octree rasterization: accelerating high-quality out-of-core GPU volume rendering

      Liu, Baoquan; Clapworthy, Gordon J.; Dong, Feng; Prakash, Edmond C.; University of Bedfordshire (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012-08-10)
      We present a novel approach for GPU-based high quality volume rendering of large out-of-core volume data. By focusing on the locations and costs of ray traversal, we are able to significantly reduce the rendering time over traditional algorithms. We store a volume in an octree (of bricks); in addition, every brick is further split into regular macro-cells. Our solutions move the branch-intensive accelerating structure traversal out of the GPU raycasting loop and introduce an efficient empty-space culling method by rasterizing the proxy geometry of a view-dependent cut of the octree nodes. This rasterization pass can capture all of the bricks that the ray penetrates in a per-pixel list. Since the per-pixel list is captured in a front-to-back order, our raycasting pass needs only to cast rays inside the tighter ray segments. As a result, we achieve two levels of empty space skipping: the brick level and the macro-cell level. During evaluation and testing, this technique achieved 2 to 4 times faster rendering speed than a current state-of-the-art algorithm across a variety of data sets.
    • Omnidirectional Holoscopic 3D content generation using dual orthographic projection

      Swash, M.R.; Aggoun, Amar; Fatah, O. Abdul; Li, B.; Fernandez, Juan C. J.; Tsekleves, Emmanuel; Brunel University; University of Bedfordshire (IEEE, 2013-06)
      In recent years there has been a considerable amount of development work been made in the area of Three-Dimensional (3D) imaging systems and displays. Such systems have attracted the attention and have been widely consumed by both home and professional users in sectors such as entertainment and medicine. However, computer generated 3D content remains a challenge as the 3D scene construction requires contributions from thousands of micro images “also known as elemental images”. Rendering microlens images is very time-consuming because each microlens image is rendered by a perspective or orthographic pinhole camera in a computer generated environment. In this paper we propose and present the development of a new method to simplify and speed-up the rendering process in computer graphics. We also describe omnidirectional 3D image recoding using a two-layer orthographic camera. Results show that it's rendering performance makes it an ideal candidate for real-time/interactive 3D content visualization application(s).
    • Opacity volume based halo generation for enhancing depth perception

      Tao, Yubo; Lin, Hai; Dong, Feng; Clapworthy, Gordon J. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011-09)
    • Optimal 3D surface reconstruction from multiview photographic images

      Prakoonwit, Simant; Benjamin, Ralph (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2009-11)
      This paper describes a new method for reconstructing 3D surface using a small number, e.g. 10, of 2D photographic images. The images are taken at different viewing directions by a perspective camera with full prior knowledge of the camera configurations. The reconstructed object's surface is represented as a set of triangular facets. We empirically demonstrate that if the viewing directions are uniformly distributed around the object's viewing sphere, then the reconstructed 3D points optimally cluster closely on the highly curved part of the surface and are widely spread on smooth or flat parts. The advantage of this property is that the reconstructed points along a surface or a contour generator are not under sampled or underrepresented because surfaces or contours should be sampled or represented with more densely points where their curvatures are high. The more complex the contour's shape, the greater the number of points is automatically generated by the proposed method. Given that the viewing directions are uniformly distributed, the number and distribution of the reconstructed points depend on the shape or the curvature of the surface regardless of the size of the surface of the object.
    • Parallel centerline extraction on the GPU

      Liu, Baoquan; Telea, Alexandru C.; Roerdink, Jos B.T.M.; Clapworthy, Gordon J.; Williams, David; Yang, Po; Dong, Feng; Codreanu, Valeriu; Chiarini, Alessandro; University of Bedfordshire; et al. (Elsevier, 2014-06)
      Centerline extraction is important in a variety of visualization applications including shape analysis, geometry processing, and virtual endoscopy. Centerlines allow accurate measurements of length along winding tubular structures, assist automatic virtual navigation, and provide a path-planning system to control the movement and orientation of a virtual camera. However, efficiently computing centerlines with the desired accuracy has been a major challenge. Existing centerline methods are either not fast enough or not accurate enough for interactive application to complex 3D shapes. Some methods based on distance mapping are accurate, but these are sequential algorithms which have limited performance when running on the CPU. To our knowledge, there is no accurate parallel centerline algorithm that can take advantage of modern many-core parallel computing resources, such as GPUs, to perform automatic centerline extraction from large data volumes at interactive speed and with high accuracy. In this paper, we present a new parallel centerline extraction algorithm suitable for implementation on a GPU to produce highly accurate, 26-connected, one-voxel-thick centerlines at interactive speed. The resulting centerlines are as accurate as those produced by a state-of-the-art sequential CPU method [40], while being computed hundreds of times faster. Applications to fly through path planning and virtual endoscopy are discussed. Experimental results demonstrating centeredness, robustness and efficiency are presented.
    • Performance analysis of a generalized and autonomous DRX scheme

      Liu, Enjie; Ren, Weili; University of Bedfordshire (IEEE, 2014-07)
      A generalized and autonomous DRX (discontinuous reception) scheme, applicable to both 3GPP and IEEE 802.16e standards, is analyzed by two - level Markov chain modeling along with the ETSI packet traffic model. Numerical analysis showed that this scheme is capable of autonomously adjusting DRX cycle to keep up with changing UE activity level with no signaling overhead increase, thus produces a better tuned DRX operation. Quantitative comparison with the power saving schemes of 3GPP and 802.16e standards demonstrated that it is advantageous over and generalization of these power saving schemes.
    • Performance simulations of moving target search algorithms

      Loh, Peter K. K.; Prakash, Edmond C. (Hindawi, 2009)
      The design of appropriate moving target search (MTS) algorithms for computer-generated bots poses serious challenges as they have to satisfy stringent requirements that include computation and execution efficiency. In this paper, we investigate the performance and behaviour of existing moving target search algorithms when applied to search-and-capture gaming scenarios. As part of the investigation, we also introduce a novel algorithm known as abstraction MTS. We conduct performance simulations with a game bot and moving target within randomly generated mazes of increasing sizes and reveal that abstraction MTS exhibits competitive performance even with large problem spaces.