Light transmission through a curved dielectric rod of rectangular cross section embedded in different dielectrics is analyzed in closed, though approximate form. We distinguish three ranges: (i) Small cross section guides such as a thin glass ribbon surrounded by air—Making its width 1 percent of the wavelength, most of the power travels outside of the glass; the attenuation coefficient of the guide is two orders of magnitude smaller than that of glass, and the radius of curvature that doubles the straight guide loss is around 10,000Λ. (ii) Medium cross section guide for integration optics—It is only a few microns on the side and capable of guiding a single mode either in low loss bends with short radii of curvature or in a high Q closed loop useful for filters. Q's of the order of 108 are theoretically achievable in loops with radii ranging from 0.04 to 1 mm, if the percentage refractive index difference between guide and surrounding dielectric lies between 0.1 and 0.01. (iii) Large cross section guides—They are multimode and are used in fiber optics. Conversion to higher order modes are found more significant than radiation loss resulting from curvature.

Bends in optical dielectric guides

MPEG-4 is the multimedia standard for combining interactivity, natural and synthetic digital video, audio and computer-graphics Typical applications are: internet, video conferencing, mobile videophones, multimedia cooperative work, teleteaching and games With MPEG-4 the next step from block-based video (ISO/IEC MPEG-1, MPEG-2, CCITT H261, ITU-T H263) to arbitrarily-shaped visual objects is taken This significant step demands a new methodology for system analysis and design to meet the considerably higher flexibility of MPEG-4 Motion estimation is a central part of MPEG-1/2/4 and H261/H263 video compression standards and has attracted much attention in research and industry, for the following reasons: it is computationally the most demanding algorithm of a video encoder (about 60-80% of the total computation time), it has a high impact on the visual quality of a video encoder, and it is not standardized, thus being open to competition Algorithms, Complexity Analysis, and VLSI Architectures for MPEG-4 Motion Estimation covers in detail every single step in the design of a MPEG-1/2/4 or H261/H263 compliant video encoder: Fast motion estimation algorithms Complexity analysis tools Detailed complexity analysis of a software implementation of MPEG-4 video Complexity and visual quality analysis of fast motion estimation algorithms within MPEG-4 Design space on motion estimation VLSI architectures Detailed VLSI design examples of (1) a high throughput and (2) a low-power MPEG-4 motion estimator Algorithms, Complexity Analysis and VLSI Architectures for MPEG-4 Motion Estimation is an important introduction to numerous algorithmic, architectural and system design aspects of the multimedia standard MPEG-4 As such, all researchers, students and practitioners working in image processing, video coding or system and VLSI design will find this book of interest

Algorithms, Complexity Analysis and VLSI Architectures for MPEG-4 Motion Estimation

We present an algorithm and a hardware architecture for block-based motion estimation that involves transforming video sequences from a multibit to a one-bit/pixel representation and then applying conventional motion estimation search strategies. This results in substantial reductions in arithmetic and hardware complexity and reduced power consumption, while maintaining good compression performance. Experimental results and a custom hardware design using a linear array of processing elements are also presented.

Low-complexity block-based motion estimation via one-bit transforms

Videoconferencing is an important global application-it enables people around the globe to interact when distance separates them. In order for the participants in a videoconference call to interact naturally, the end-to-end delay should be below human perception; even though an objective and unique figure cannot be set, 100 ms is widely recognized as the desired one-way delay requirement for interaction. Since the global propagation delay can be about 100 ms, the actual end-to-end delay budget available to the system designer (excluding propagation delay) can be no more than 10 ms. We identify the components of the end-to-end delay in various configurations with the objective of understanding how it can be kept below the desired 10-ms bound. We analyze these components step-by-step through six system configurations obtained by combining three generic network architectures with two video encoding schemes. We study the transmission of raw video and variable bit rate (VBR) MPEG video encoding over (1) circuit switching; (2) synchronous packet switching; and (3) asynchronous packet switching. In addition, we show that constant bit rate (CBR) MPEG encoding delivers unacceptable delay-on the order of the group of pictures (GOP) time interval-when maximizing the quality for static scenes. This study aims at showing that having a global common time reference, together with time-driven priority (TDP) and VBR MPEG video encoding, provides adequate end-to-end delay, which is (1) below 10 ms; (2) independent of the network instant load; and (3) independent of the connection rate. The resulting end-to-end delay (excluding propagation delay) can be smaller than the video frame period, which is better than what can be obtained with circuit switching.

End-to-end delay analysis of videoconferencing over packet-switched networks

An image acquisition sensor of a digital image acquisition apparatus is coupled to imaging optics for acquiring a sequence of images. Images acquired by the sensor are stored. A motion detector causes the sensor to cease capture of an image when the degree of movement in acquiring the image exceeds a threshold. A controller selectively transfers acquired images for storage. A motion extractor determines motion parameters of a selected, stored image. An image re-constructor corrects the selected image with associated motion parameters. A selected plurality of images nominally of the same scene are merged and corrected by the image re-constructor to produce a high quality image of the scene.

Image Acquisition Method and Apparatus

A simple adaptive block matching algorithm is proposed for motion estimation. The proposed method exploits the motion correlation of spatially neighbouring blocks to determine the search origin and adjusts the search range according to different motion content of the block. Simulation results show that the proposed algorithm achieves nearly the same MSE performance as the full-search method but requires ~80% less computation.

Adaptive block matching motion estimation algorithm for video coding

Motion estimation/compensation techniques are extensively used in video compression because of their abilities to exploit the high temporal correlation between successive frames of an image sequence. We first propose a new matching criterion called bit-plane matching (BPM) for distance measurement in the block matching algorithm. This criterion not only considers the magnitude but also the directive information of the pixel elements in the block. A simple adaptive block matching algorithm is also developed to adjust the search origin and search range at a block-by-block basis. Simulation results show that the proposed algorithm achieves similar MSE performance for motion-predicted images but requires about 8 times less the number of computations than the full-search method.

Adaptive block matching motion estimation algorithm using bit-plane matching

Cell loss is inevitable in ATM networks due to network congestion and appears to be a critical factor affecting the quality of the video signal. For transmitting MPEG video over ATM networks, cell loss causes error propagation in both the spatial and temporal domain, which in turn leads to severe degradation in the image quality. We first introduce a structural method for packing MPEG video bit-stream into ATM cells. With this method, the impact of cell loss can be limited to the lost cells only. A cell loss compensation method called modified boundary matching algorithm is then proposed for transmitting the MPEG video bit-stream in ATM networks. Simulation results demonstrate that the proposed method yields satisfactory results even when the cell loss rate is very high.

http://ieeexplore.ieee.org/iel3/3734/10924/00502742.pdf

Cell loss concealment method for MPEG video in ATM networks

A new type of optical waveguide is proposed. It consists of a thin film of transparent dielectric supporting the surface E0 wave mode. With properly chosen dimensions, attenuation of a few decibels per kilometre is theoretically achievable. A design is suggested which gives the guide the required flexibility for negotiating bends.

New type of waveguide for light and infrared waves

Cell loss is a critical problem for transmission of video over ATM networks We first introduce a structural method for packing MPEG video bit-stream into ATM cells With this method, the impact of cell loss can be limited to the lost cells only A compensation method called the modified boundary matching algorithm is then proposed for recovery of the lost video information Simulation results demonstrate that the proposed method yields satisfactory results even when the cell loss rate is very high

Loss recovery techniques for transmission of MPEG video over ATM networks

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