Integral imaging is a technique capable of displaying 3D images with continuous parallax in full natural color. It is one of the most promising methods for producing smooth 3D images. Extracting depth information from integral image has various applications ranging from remote inspection, robotic vision, medical imaging, virtual reality, to content-based image coding and manipulation for integral imaging based 3D TV. This paper presents a method of generating a depth map from unidirectional integral images through viewpoint image extraction and using a hybrid disparity analysis algorithm combining multi-baseline, neighborhood constraint and relaxation strategies. It is shown that a depth map having few areas of uncertainty can be obtained from both computer and photographically generated integral images using this approach. The acceptable depth maps can be achieved from photographic captured integral images containing complicated object scene.

A new construction of hybrid power filters, which needs lower capacity of active component comparing with existing hybrid power filter, is proposed. In order to decrease the rating of active filter, a C-type filter is adopted which is in series with the active filter, for its high impedance at the fundamental frequency while presenting a low impedance at the harmonic frequencies. The most active power filters existed require a large power rating, while this configuration can reduce large rating of active power filter as the C-type filter carries most of the fundamental voltage. In order to be satisfied the criterion of the harmonics compensation and run in an economic way, a parameters optimization of C-type filter is put forwarded. The simulation is made in this paper, which is with the optimized parameters. It is confirmed by analysis and simulation that the combined power filter with optimized C-type filter runs in an effective and economic way in the harmonic compensation.

Currently, several 3D stereoscopic projection systems exist where the audience are required to wear some sort of visual aid. A number of research groups are investigating autostereoscopic displays, as these systems are more acceptable to the casual observer as they require no additional visual aids. Most autostereoscopic projection displays are stereoscopic or employ multiview techniques. Both approaches are limited in their ability to present realistic 3D images with natural viewing attributes. The paper reports on the results of experiments carried out to evaluate large-scale 3D integral projection. Two projection arrangements (single-lens un-corrected optics and double-lens corrected optics) are reported and their advantages and disadvantages described. Live capture and computer generated integral images have been projected back to “life-size.” The observer can interact with the 3D image by reaching into the presented volumetric image space.

A novel depth estimation algorithm is proposed based on the special characteristics of 3D integral images. It includes three processes to obtain a depth map: initialization, refining and pickup. Experiments show it can provide estimates on moderate complex situations.

A VLSI architecture for the three-dimensional discrete cosine transform (3D DCT) is proposed. The 3D DCT is decomposed into 1D DCTs computed in each of the three dimensions. The focus of this paper is in the design of the matrix transpose required prior to the computation of the final 1D DCT which corresponds to the third dimension. This matrix transpose is divided into N memory units each performing the row-column transpose and switching networks to allow correct read and write. This architecture uses 3N multiplier-accumulators and N+1 (N×N)-words memory transpose to evaluate an (N×N×N)-point DCT at a rate of one complete 3D transform per N3 clock cycles, where N is even

For computer generated integral images, a transition line can be observed when the viewer shifts parallel to the lens sheet and reaches the edge of current viewing zone during viewing. This is due to the transition from current viewing zone to the next. The images generated using conventional algorithms will suffer from big transition zone, which damages the replaying visual effect and greatly decreases the effective viewing width. This phenomenon is especially apparent for large size images. The conventional computer generation algorithms of integral images use the same boundary configuration as the micro-lenses, which is straightforward and easy to be implemented, but the cause of large transition zone and narrow viewing angle. This paper presents a novel micro-image configuration and algorithm to solve the problem. In the new algorithm, the boundaries of micro-images are not confined by the physical boundaries but normally larger than them. To achieve the maximum effective viewing width, each micro-image is arranged according to the rules decided by several constraints. The considerations in the selection of optimal parameters are discussed, and new definitions related to this issue are given.

An evaluation of the retention of continuous parallax in pixelated integral three-dimensional image displays is presented. The integral image capture process is first considered, to provide a starting point for the investigation. The complementary display system is then examined in detail. The viewing geometry of the display system is analyzed to provide a foundation for the work to follow, and an experimental investigation and simulations of the characteristics of emitted ray bundles are presented. Next, an analytical model of decoding lenslet array operation is derived, leading to an understanding of the process responsible for production of continuous parallax in replay. It is found that if the lateral resolution of the lenslet is matched to that of the display, continuous parallax is retained in the replayed image, where the finite aberration-limited resolution of the lenslet acts to produce a low-pass reconstruction filter. A condition is derived for optimal continuous parallax in replay, based on a relationship between pixel width and lenslet rms spot size.

A software model for an optical system incorporating microlens arrays to capture and replay an object or scene in real 3D is presented. The imaging methodology is usually referred to as "Integral Photography" (IP) or "Integral Imaging" (II). A brief description of II is given and the single-stage optical capture system, which the software model attempts to emulate, is discussed. The software design aims to reproduce the real optics system to produce rendered static and dynamic images in integral format. The effects and limitations caused by the relatively low display resolutions are addressed and their effect on image quality considered. The Phong illumination model along with the Flat, Gouraud and Phong shading techniques are employed and their respective applications to II are explained.

The paper presents the study and the design of air embedded electronic control system that allows diesel engine driven stand-alone synchronous generators to operate at variable (optimum) speed. A new control strategy has been developed, based on passivity theory for the PWM inverter control and a fuzzy, logic fuel admission control system, to overcome the nonlinearity introduced into the system by the diesel engine. In order to use the passivity theory approach, the system was described in Euler-Lagrange form, such systems representing the outcome of the powerful variational modelling method. MATLAB software was used for the complete power and control system design and simulation and a novel approach was adopted for the FPGA implementation of the digital controller. The method is based on using Handel-C, an innovative language for implementing algorithms in hardware, architectural design space exploration and hardware/software co-design. The new PWM passivity based controller was designed, successfully simulated and is currently being implemented in a Virtex Xilinx FPGA. Experimental tests are being carried out to validate the behaviour of the controller. The main achievements of the new control system relate to the efficient maintenance of the output voltage at the desired magnitude and frequency independent of the rotational speed of the generator, under variable loading conditions, thus allowing variable (optimum) speed operation of the diesel engine.

This paper presents for the first time, a theory for obtaining the optimum pixel grouping for improving the coherence and the shadow cache in integral 3D ray-tracing in order to reduce execution time. A theoretical study of the number of shadow cache hits with respect to the properties of the lenses and the shadow size and its location is discussed with analysis for three different styles of pixel grouping in order to obtain the optimum grouping. The first style traces rows of pixels in the horizontal direction, the second traces similar pixels in adjacent lenses in the horizontal direction, and the third traces columns of pixels in the vertical direction. The optimum grouping is a combination of all three dependant up on the number of cache hits in each. Experimental results show validation of the theory and tests on benchmark scenes show that up to a 37% improvement in execution time can be achieved by proper pixel grouping.

This paper presents a fast DC link voltage controller implemented with FPGA technology. The controller is designed for maintaining quality voltage supply in stand-alone diesel engine driven permanent magnet generator systems. Functional simulation and practical tests with a laboratory system were carried out and the results have shown that the controller is successful in quickly regulating the DC voltage level and keeping an almost constant voltage. The developed controller has the advantages of fast response, short developing period and low cost.

The development of 3D TV systems and displays for public use require that several important criteria be satisfied. The criteria are that the perceived resolution is as good as existing 2D TV, the image must be in full natural colour, compatibility with current 2D systems in terms of frame rate and transmission data must be ensured, human-factors concerns must be satisfied and seamless autostereoscopic viewing provided. There are several candidate 3D technologies, for example stereoscopic multiview, holographic and integral imaging that endeavor to satisfy the technological and other conditions.The perceived advantages of integral imaging are that the 3D data can be captured by a single aperture camera, the display is a scaled 3D optical model, and in viewing accommodation and convergence are as in normal sighting (natural) thereby preventing possible eye strain. Consequently it appears to be ideal for prolonged human use. The technological factors that inhibited the possible use of integral imaging for TV display have been shown to be less intractable than at first thought. For example compression algorithms are available such that terrestrial bandwidth is perfectly suitable for transmission purposes. Real-time computer generation of integral images is feasible and the high-resolution LCD panels currently available are sufficient to enable high contrast and high quality image display.

At De Montfort University the imaging technologies group have developed an integral imaging system capable of real time capture and replay. The system has many advantages compared with other 3D capture and display techniques, however one issue that has not been adequately addressed is the measurement of the fidelity of replayed 3D images where some distortion has occurred. This paper presents a method for producing a viewing angle-dependent PSNR metric based on extraction of optical model data as conventional images. The technique produces image quality measurements which are more relevant to the volume spatial content of an integral image than a conventional fidelity metric applied to the raw, optically encoded spatial distribution. Comparisons of the previous, single metric with the new angle-dependent metric are made when used in assessing the performance of a 3D-DCT based compression scheme, and the utility of the extra information provided by the angle dependent PSNR is considered.

The paper presents a new approach to the modelling, simulation, digital controller design and implementation of a complete induction motor electric drive system. The design approach is to use a very high speed integrated circuit hardware description language (VHDL) as a unique EDA environment for system modelling, evaluation and controller design. Simulation and experimental results are presented, proving the validity of the novel approach when applied to a vector controlled induction motor system. The advantages of using VHDL for a drive modelling and control strategy implementation are enumerated.

Integral imaging is a technique capable of displaying images with continuous parallax in full natural color. This paper presents a modified multi-baseline method for extracting depth information from unidirectional integral images. The method involves first extracting sub-images from the integral image. A sub-image is constructed by extracting one pixel from each micro-lens rather than a macro-block of pixels corresponding to a micro-lens unit. A new mathematical expression giving the relationship between object depth and the corresponding sub-image pair displacement is derived by geometrically analyzing the three-dimensional image recording process. A correlation- based matching technique is used fo find the disparity between two sub-images. In order to improve the disparity analysis, a modified multi-baseline technique where the baseline is defined as the distance between two corresponding pixels in different sub-images is adopted. The effectiveness of this modified multi-baseline technique in removing the mismatching caused by similar patterns in object scenes has been proven by analysis and experiment results. The developed depth extraction method is validated and applied to both photographic and computer generated unidirectional integral images. The depth estimation solution gives a precise description of object thickness with an error of less than 1.0% from the photographic image in the example.

Integral imaging is employed as part of a three-dimensional imaging system, allowing the display of full colour images with continuous parallax within a wide viewing zone. A significant quantity of data is required to represent a captured integral 3D image with high resolution. A lossy compression scheme has been developed based on the use of a 3D-DCT, which make possible efficient storage and transmission of such images, while maintaining all information necessary to produce a high quality 3D display. In this paper, a novel approach to the problem of compressing the significant quantity of data required to represent integral 3D images is presented. The algorithm is based on using a variable number of microlens images (or sub-images) in the computation of the 3D-DCT. It involves segmentation of the planar mean image formed by the mean values of the microlens images and it takes advantage of the high cross-correlation between the sub-images generated by the microlens array. The algorithm has been simulated on several integral 3D images. It was found that the proposed algorithm improves the rate-distortion performance when compared to baseline JPEG and previously reported 3D-DCT compression scheme with respect to compression ratio and subjective and objective image quality.

This paper is to present an advanced hybrid variable speed controller for controlling stand-alone diesel engine driven permanent generator systems to keep voltage and frequency constant and to maintain efficient operation of the connected loads. The controller is designed based on a hybrid method; a fuzzy logic core is developed and embedded in the variable speed controller combined with a conventional control method. By using the hybrid control method for the design of the variable speed controller, the hardware implementation can be accommodated in a less expensive, compact FPGA device. Consequently a highly robust low cost controller is made available. Simulation and experimental studies have shown that the resulting controller is effective and provides high stability.

The Imaging Technologies group at De Montfort University has developed an integral 3D imaging system, which is seen as the most likely vehicle for 3D television avoiding psychological effects. To create real fascinating three-dimensional television programs, a virtual studio that performs the task of generating, editing and integrating the 3D contents involving virtual and real scenes is required. The paper presents, for the first time, the procedures, factors and methods of integrating computer-generated virtual scenes with real objects captured using the 3D integral imaging camera system. The method of computer generation of 3D integral images, where the lens array is modelled instead of the physical camera is described. In the model each micro-lens that captures different elemental images of the virtual scene is treated as an extended pinhole camera. An integration process named integrated rendering is illustrated. Detailed discussion and deep investigation are focused on depth extraction from captured integral 3D images. The depth calculation method from the disparity and the multiple baseline method that is used to improve the precision of depth estimation are also presented. The concept of colour SSD and its further improvement in the precision is proposed and verified.

Over the past decade there has emerged a growing number of sculptors, from around the globe, who have found a use for the computer in their research and practice. For some it offers a design tool but for others it has become a new media. A new integral imaging system capable of real-time capture and replay and methods of computer generation of synthetic integral images has recently been developed. Keith Brown, a sculptor was intrigued at the possibilities this offers as a means through which to realize cyber-sculptures as true 3D optical constructs. This paper presents the most recent results of the collaboration between Keith Brown and the Imaging Technologies Group at De Montfort University.

At De Montfort University the imaging technologies group have developed an integral imaging system capable of real time capture and replay. The system has many advantages compared with other 3D capture and display techniques, however one issue that has not been adequately addressed is the measurement of the fidelity of replayed 3D images where some distortion has occurred. This paper presents a method for producing a viewing angle-dependent PSNR metric based on extraction of optical model data as conventional images. The technique produces image quality measurements which are more relevant to the volume spatial content of an integral image than a conventional fidelity metric applied to the raw, optically encoded spatial distribution. Comparisons of the previous, single metric with the new angle-dependent metric are made when used in assessing the performance of a 3D-DCT based compression scheme, and the utility of the extra information provided by the angle dependent PSNR is considered.