• 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.
    • Subspace-based SNR estimator for OFDM system under different channel conditions

      Li, Wei; Zhang, Yue; Zhang, Yuan; Huang, Li-Ke; Cosmas, John; Maple, Carsten; University of Bedfordshire (IEEE, 2013-06)
      Signal-to-noise ratio (SNR) estimation plays an important role to adaptive modulation in Evolved Multimedia Broadcast Multicast Services (eMBMS). Based on the knowledge that the received signal space consists of signal subspace and noise subspace, we propose a subspace-based SNR estimation solution to cope with the time-varying channel with frequency selective effect and different OFDM pilot structure situations in eMBMS. The simulation is carried out on both PC and Aeroflex PXI platform. Simulation results show this proposed method gives good performance with different eMBMS pilot length and time-varying channels.
    • Adaptive 3D-DCT based compression algorithms for integral images

      Mehanna, A.; Aggoun, Amar; Fatah, O. Abdul; Swash, M.R.; Tsekleves, Emmanuel; Brunel University; University of Bedfordshire (IEEE, 2013)
      This paper proposes a novel mean adaptive 3DDCT algorithm for 3D content to achieve the optimal result by trading of quality and compression of 3D image. The proposed method enables users to adjust the compression rate according to application areas by applying small blocks to the more detailing area (non -stationary regions) and larger blocks to the background or less details area (homogenous regions) [1]. This proposed method “Mean Adaptive 3D-DCT” is applied on Holoscopic 3D images also known as Integral Images. In addition, the experiment results prove the method is applicable to any 3D content.
    • 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
    • Diode-based IQ imbalance estimation in direct conversion transmitters

      Xiong, Jian; Zhang, Yue; Li, Wei; Wang, Jin; Huang, Li-Ke; Maple, Carsten; University of Bedfordshire; Aeroflex, Stevenage; Shanghai Jiao Tong University (IEEE, 2014-02)
      Direct conversion transmitters are widely used in wireless systems for their inherent features of being simple and low cost. In this architecture, the inphase (I branch) and quadrature signal (Q branch) will be unconverted to the RF frequency band by quadrature modulation. However, the drawback of the direct conversion architecture is that it is sensitive to IQ imbalance caused by the impairment of analogue devices in I and Q branches. It then results in interferences in mirror frequencies which degrades the signal quality. Therefore, the accurate measurement of IQ imbalance is crucial. A diode-based method to measure the broadband IQ imbalance is proposed which does not need additional measurement instruments. Measurement results show the effectiveness of this method
    • 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).
    • Three-dimensional integral image reconstruction based on viewpoint interpolation

      Abdul Fatah, O.; Lanigan, Peter M. P.; Aggoun, Amar; Swash, M.R.; Alazawi, E.; Li, B.; Fernandez, Juan C. J.; Chen, D.; Tsekleves, Emmanuel; Brunel University; et al. (IEEE, 2013-07)
      This paper presents new algorithm for improving the visual definition quality of real integral images computationally through image reconstructing. The proposed algorithm takes advantage of true 3D “Integral imaging”. A real world scene is recorded based on the fly's eye technique, which is simulated by an array of microlenses.. The proposed method works on orthographic viewpoint images, where shift-and-integration of the neighbouring viewpoints are used with quadratic interpolation to increase the visual quality on the final image. This process returns a standard photographic image with enhanced image quality. Detailed experiments have been conducted to demonstrate the effectiveness of proposed method and results are offered.
    • Distributed pixel mapping for refining dark area in parallax barriers based holoscopic 3D Display

      Swash, M.R.; Aggoun, Amar; Fatah, O. Abdul; Fernandez, Juan C. J.; Alazawi, E.; Tsekleves, Emmanuel; Brunel University; University of Bedfordshire (IEEE, 2013-12)
      Autostereoscopic 3D Display is robustly developed and available in the market for both home and professional users. However 3D resolution with acceptable 3D image quality remains a great challenge. This paper proposes a novel pixel mapping method for refining dark areas between two pinholes by distributing it into 3 times smaller dark areas and creating micro-pinholes in parallax barriers based holoscopic 3D displays. The proposed method allows to project RED, GREEN, BLUE subpixels separately from 3 different pinholes and it distributes the dark spaces into 3 times smaller dark spaces, which become unnoticeable and improves quality of the constructed holoscopic 3D scene significantly. Parallax barrier technology refers to a pinhole sheet or device placed in front or back of a liquid crystal display, allowing to project viewpoint pixels into space that reconstructs a holoscopic 3D scene in space. The holoscopic technology mimics the imaging system of insects, such as the fly, utilizing a single camera, equipped with a large number of micro-lenses or pinholes, to capture a scene, offering rich parallax information and enhanced 3D feeling without the need of wearing specific eyewear.
    • Holoscopic 3D image rendering for Autostereoscopic Multiview 3D Display

      Swash, M.R.; Aggoun, Amar; Fatah, O. Abdul; Li, B.; Fernandez, Juan C. J.; Tsekleves, Emmanuel; Brunel University; University of Bedfordshire (IEEE, 2013-06)
      The Autostereoscopic Multiview 3D Display is robustly developed and widely adopted by both home and professional users however Multiview 3D content generation remains a great challenge. This paper proposes a novel method for Multiview 3D content generation and it describes the necessary steps for Holoscopic 3D image rendering for autostereoscopic Multiview 3D display. The Holoscopic imaging technology mimics the imaging system of insects, such as the fly, utilizing a single camera, equipped with a large number of micro-lenses, to capture a scene, offering rich parallax information and enhanced 3D feeling without the need of wearing specific eyewear. In addition a 3D pixel mapping/conversion algorithm has been developed that is supported by the Multiview 3D display.
    • Immersive 3D holoscopic video system

      Aggoun, Amar; Tsekleves, Emmanuel; Swash, M.R.; Zarpalas, D.; Dimou, A.; Daras, P.; Nunes, P.; Soares, L.D.; Brunel University; University of Bedfordshire (IEEE, 2013-02)
      We demonstrated a 3D holoscopic video system for 3DTV application. We showed that using a field lens and a square aperture significantly reduces the vignetting problem associated with a relay system and achieves over 95 percent fill factor. The main problem for such a relay system is the nonlinear distortion during the 3D image capturing, which can seriously affect the reconstruction process for a 3D display. The nonlinear distortion mainly includes lens radial distortion (intrinsic) and microlens array perspective distortion (extrinsic). This is the task of future work. Our results also show that the SS coding approach performs better than the standard HEVC scheme. Furthermore, we show that search and retrieval performance relies on the depth map's quality and that the multimodal fusion boosts the retrieval performance.
    • Pre-processing of holoscopic 3D image for autostereoscopic 3D displays

      Swash, M.R.; Aggoun, Amar; Fatah, O. Abdul; Li, B.; Fernandez, Juan C. J.; Alazawi, E.; Tsekleves, Emmanuel; University of Bedfordshire; Brunel University (2013-12)
      Holoscopic 3D imaging also known as Integral imaging is an attractive technique for creating full colour 3D optical models that exist in space independently of the viewer. The constructed 3D scene exhibits continuous parallax throughout the viewing zone. In order to achieve depth control, robust and real-time, a single aperture holoscopic 3D imaging camera is used for recording holoscopic 3D image using a regularly spaced array of microlens arrays, which view the scene at a slightly different angle to its neighbour. However, the main problem is that the microlens array introduces a dark borders in the recorded image and this causes errors at playback on the holoscopic 3D Display. This paper proposes a reference based pre-processing of holoscopic 3D image for autostereoscopic holoscopic 3D displays. The proposed method takes advantages of microlens as reference point to detect amount of introduced dark borders and reduce/remove them from the holoscopic 3D image.
    • Adaptive depth map estimation from 3D integral image

      Alazawi, E.; Aggoun, Amar; Abbod, M.; Fatah, O. Abdul; Swash, M.R.; Brunel University; University of Bedfordshire (IEEE, 2013-06)
      Integral Imaging (InIm) is one of the most promising technologies for producing full color 3-D images with full parallax. InIm requires only one recording in obtaining 3D information and therefore no calibration is necessary to acquire depth values. The compactness of using InIm in depth measurement has been attracting attention as a novel depth extraction technique. In this paper, an algorithm for depth extraction that builds on previous work by the authors is presented. Three main problems in depth map estimation from InIm have been solved; the uncertainty and region homogeneity at image location where errors commonly appear in disparity process, dissimilar displacements within the matching block around object borders, object segmentation. This method is based on the distribution of the sample variance in sub-dividing non-overlapping blocks. A descriptor which is unique and distinctive for each feature on InIm has been achieved. Comparing to state-of-the-art techniques, it is shown that the proposed algorithm has improvements on two aspects: depth map extraction level, computational complexity.
    • Scene depth extraction from Holoscopic Imaging technology

      Alazawi, E.; Aggoun, Amar; Abbod, M.; Swash, M.R.; Abdul Fatah, O.; Fernandez, Juan C. J.; University of Bedfordshire; Brunel University (IEEE, 2013-10)
      3D Holoscopic Imaging (3DHI) is a promising technique for viewing natural continuous parallax 3D objects within a wide viewing zone using the principle of “Fly's eye”. The 3D content is captured using a single aperture camera in real-time and represents a true volume spatial optical model of the object scene. The 3D content viewed by multiple viewers independently of their position, without 3D eyewear glasses. The 3DHI technique merely requires a single recording that the acquisition of the 3D information and the compactness of depth measurement that is used has been attracting attention as a novel depth extraction technique. This paper presents a new corresponding and matching technique based on a novel automatic Feature-Match Selection (FMS) algorithm. The aim of this algorithm is to estimate and extract an accurate full parallax 3D model form from a 3D Omni-directional Holoscopic Imaging (3DOHI) system. The basis for the novelty of the paper is on two contributions: feature blocks selection and corresponding automatic optimization process. There are solutions for three main problems related to the depth map estimation from 3DHI: uncertainty and region homogeneity at image location, dissimilar displacements within the matching block around object borders, and computational complexity.
    • Generating stereoscopic 3D from holoscopic 3D

      Fatah, O. Abdul; Aggoun, Amar; Swash, M.R.; Alazawi, E.; Li, B.; Fernandez, Juan C. J.; Chen, D.; Tsekleves, Emmanuel; University of Bedfordshire; Brunel University (IEEE, 2013-10)
      In this paper a single aperture motion picture camera based on holoscopic imaging used to generate high-resolution stereoscopic image. The idea of single aperture camera reduces the very cumbersome and expensive of dual cameras in stereoscopic production. The camera is known as light field camera, which was first proposed in 1908 by lippmann [1]. The rendering method relied on up-sampling, shift and integrating of different views to extract stereo images. This is the first experiment attempted to generate stereo form holoscopic content on motion capturing, where researchers so far have been experimenting on still images. In this paper presents motion picture image rendering on holoscopic content to generate content for stereoscopic systems. We have carried out experiments with focused plenoptic camera on a single stage omnidirectional integral camera arrangement with capturing both horizontal and vertical parallax, using a low cost lens array and relay lens. Our results show an improvement in the resolution of images with artefact free and also the rendered stereo content are played back on polarized stereoscopic system and anaglyph system to perceive the 3D depth using filter glasses in our experimental section.
    • An algorithm for accurate taillight detection at night

      Boonsim, Noppakun; Prakoonwit, Simant; University of Bedfordshire (Foundation of Computer Science, 2014-08)
      Vehicle detection is an important process of many advance driver assistance system (ADAS) such as forward collision avoidance, Time to collision (TTC) and Intelligence headlight control (IHC). This paper presents a new algorithm to detect a vehicle ahead by using taillight pair. First, the proposed method extracts taillight candidate regions by filtering taillight colour regions and applying morphological operations. Second, pairing each candidates and pair symmetry analysis steps are implemented in order to have taillight positions. The aim of this work is to improve the accuracy of taillight detection at night with many bright spot candidates from streetlamps and other factors from complex scenes. Experiments on still images dataset show that the proposed algorithm can improve the taillight detection accuracy rate and robust under limited light images.
    • Towards multiple 3D bone surface identification and reconstruction using few 2D X-ray images for intraoperative applications

      Prakoonwit, Simant; University of Bedfordshire (IGI Global, 2014-06)
      This article discusses a possible method to use a small number, e.g. 5, of conventional 2D X-ray images to reconstruct multiple 3D bone surfaces intraoperatively. Each bone’s edge contours in X-ray images are automatically identified. Sparse 3D landmark points of each bone are automatically reconstructed by pairing the 2D X-ray images. The reconstructed landmark point distribution on a surface is approximately optimal covering main characteristics of the surface. A statistical shape model, dense point distribution model (DPDM), is then used to fit the reconstructed optimal landmarks vertices to reconstruct a full surface of each bone separately. The reconstructed surfaces can then be visualised and manipulated by surgeons or used by surgical robotic systems.
    • 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 %.
    • Taxonomy of optimisation techniques and applications

      Maple, Carsten; Prakash, Edmond C.; Huang, Wei; Qureshi, Adnan Nabeel Abid; University of Bedfordshire (Inderscience Publishers, 2014-06)
      This paper presents a review of recent advances in optimisation techniques. Optimisation is a complex task and it is nearly impossible to identify a single technique which can act as a silver bullet in all contexts where scarcity and limitation of resources and constraints exist. The list of individual optimisation methods, their combinations and hybridisations is endless and, hence, it is imperative to classify them based on common attributes and highlight some of the salient industrial and research domains where they have been implemented. This paper concentrates on application areas of the different optimisation techniques in particular, with the objective to establish a practical taxonomy based on the combination of heuristic or non-heuristic nature of algorithms, nature of design variables and nature of equations. A précis of research at the University of Bedfordshire is also given to highlight the contributions made towards optimising different industrial and engineering problems exemplifying the latest trends and research arenas.
    • Scheduling and optimisation of batch plants: model development and comparison of approaches

      Tan, Yaqing; Huang, Wei; Sun, Yanming; Yue, Yong; University of Bedfordshire (Inderscience Publishers, 2014-06)
      The application of parallel machines and storage facilities provides flexibility but raises challenges for batch plants. This research proposes a scheduling model in batch plants, considering complex real-world constraints that were seldom addressed together. Two optimisation approaches, genetic algorithm (GA) and constraint programming (CP), are applied to solve the complex batch plant scheduling problem. A case study and scalability tests are conducted to investigate different performance of GA and CP in the problem to prepare for further research application. It is found that the CP approach has a better performance in solving batch plant scheduling problems with complex constraints although it needs longer time. The ‘restart’ search strategy is better than two other search strategies for the CP approach.
    • Applying Cross-cultural theory to understand users’ preferences on interactive information retrieval platform design

      Chessum, Karen; Liu, Haiming; Frommholz, Ingo; University of Bedfordshire (University of Nottingham, School of Computer Science., 2014-09)
      In this paper we look at using culture to group users and model the users’ preference on cross cultural information retrieval, in order to investigate the relationship between the user search preferences and the user’s cultural background. Initially we review and discuss briefly website localisation. We continue by examining culture and Hofstede’s cultural dimensions. We identified a link between Hofstede’s five dimensions and user experience. We did an analogy for each of the five dimensions and developed six hypotheses from the analogies. These hypotheses were then tested by means of a user study. Whilst the key findings from the study suggest cross cultural theory can be used to model user’s preferences for information retrieval, further work still needs to be done on how cultural dimensions can be applied to inform the search interface design.