This paper is a revised version of an article by the same title and author which appeared in the April 1991 issue of Communications of the ACM. For the past few years, a joint ISO/CCITT committee known as JPEG (Joint Photographic Experts Group) has been working to establish the first international compression standard for continuous-tone still images, both grayscale and color. JPEG’s proposed standard aims to be generic, to support a wide variety of applications for continuous-tone images. To meet the differing needs of many applications, the JPEG standard includes two basic compression methods, each with various modes of operation. A DCT-based method is specified for “lossy’ ’ compression, and a predictive method for “lossless’ ’ compression. JPEG features a simple lossy technique known as the Baseline method, a subset of the other DCT-based modes of operation. The Baseline method has been by far the most widely implemented JPEG method to date, and is sufficient in its own right for a large number of applications. This article provides an overview of the JPEG standard, and focuses in detail on the Baseline method. 1

Abstract — This paper presents a tutorial overview of neural networks as signal processing tools for image compression. They are well suited to the problem of image compression due to their massively parallel and distributed architecture. Their characteristics are analogous to some of the features of our own visual system, which allow us to process visual information with much ease. For example, multilayer perceptrons can be used as nonlinear predictors in differential pulse-code modulation (DPCM). Such predictors have been shown to increase the predictive gain relative to a linear predictor. Another active area of research is in the application of Hebbian learning to the extraction of principal components, which are the basis vectors for the optimal linear Karhunen-Loève transform (KLT). These learning algorithms are iterative, have some computational advantages over standard eigendecomposition techniques, and can be made to adapt to changes in the input signal. Yet another model, the self-organizing feature map (SOFM), has been used with a great deal of success in the design of codebooks for vector quantization (VQ). The resulting codebooks are less sensitive to initial conditions than the standard LBG algorithm, and the topological ordering of the entries can be exploited to further increase coding efficiency and reduce computational complexity. I.

Abstract-This paper presents a three-dimensional, highly par-allel, optically interconnected system to process high-throughput stream data such as images. The vertical optical interconnections are realized using integrated optoelectronic devices operating at wavelengths to which silicon is transparent. These through-wafer optical signals are used to vertically optically interconnect stacked silicon circuits. The thin film optoelectronic devices are bonded directly to the stacked layers of silicon circuitry to realize self-contained vertical optical interconnections. Each integrated circuit layer contains analog interface circuitry, namely, detector amplifier and emitter driver circuitry, and digital circuitry for the network and/or processor, all of which are fabricated using a standard silicon integrated circuit foundry. These silicon circuits are post processed to integrate the thin film optoelectronics using standard, low cost, high yield microfabrication techniques. The three-dimensionally integrated architectures described herein are a network and a processor. The network has been designed to meet off-chip U 0 using a new offset cube topology coupled with naming and routing schemes. The performance of this network is comparable to that of a three-dimensional mesh. The processing architecture has been defined to minimize overhead for basic parallel operations. The system goal for this research is to develop an integrated processing node for high-throughput, low-memory applications. I.

In a system based on the imprecise-computation technique, each time-critical task is designed in such a way that it can produce a usable, approximate result in time whenever a failure or overload prevents it from producing the desired, precise result. This section describes ways to use this technique together with traditional fault-tolerance methods to reduce the costs of providing fault tolerance andenhancedavailability. Specifically, an imprecise mechanism for the generation and use of approximate results can be integrated in a natural way with traditional checkpointing and replication mechanisms. Algorithms and process structures for this integration and rules for determining when approximate results can be used in place of the desired results are discussed.

The maintenance of large raster images under spatial operations is still a major performance bottleneck. For reasons of storage space, images in a collection, such as satellite pictures in geographic information systems, are maintained in compressed form. Instead of performing a spatially selective operation on an image by first decompressing the compressed version, we propose to perform queries directly on the compressed version of the image. We suggest a compression technique that allows for the subsequent use of a data structure to guide a spatial search. In response to a range query, our algorithm delivers a compressed partial image. Experiments show that the new algorithm supports spatial queries on satellite images efficiently. In addition it is even competitive in terms of the compression that it achieves. 1. Introduction Due to the enormous data volume, the efficiency of operations is still a major bottleneck in systems that handle large raster images, such as geographic inform...

. In this paper, a teleservice for archiving and retrieving multimediadocumentsusingpublicnetworks is described.Thisteleserviceencouragesabroadrange of multimedia archiving applications. The described implementation is based on standardized multimediamailand suitable for an asynchronous access mechanism. Theoriginalityofthiswork is theintegrationofmultimediamailwithsimplestandalone archive clients for heterogeneous platforms and an archive server which is based on an object-oriented DBMS. The modeling of the server is described indepthshowingthecontributionsofobject -orienteddatabasetechnologyfortherealization of generic electronic archives that deal with structured multimedia documents. Helpfulhintsandimportantdesignsuggestionsfortheimplementationofadvanced archive functionality are provided. Furthermore, functionality for efficient access on the client side is outlined. A sample application showing a Multimedia Calendar of Events is sketched as well. 1 Introduction Advances in hardw...

New concepts such as the Application Level Framing (ALF) have been proposed to make network protocol implementations more efficient and to give the application programmer greater control over the data transmission. This paper describes early experiments with automated design and implementation of application-specific communication protocols based on the formal specification of the application using ESTEREL. A comparison is made between a hand coded JPEG player and its automated equivalent. The results show that the automated approach creates a better integrated implementation with the same level of performance. Keywords Efficient Communication Architectures, ALF, Integrated Implementation, Formal Specifications, User Level Protocols. 1.0 INTRODUCTION The rapid evolution of networking and the multiplication of new applications re-emphasizes the importance of the efficient (i.e. flexible and performant) communication supports. Implementations must be able to take maximal advantage of d...

The maintenance of large raster images under spatial operations is still a major performance bottleneck. For reasons of storage space, images in a collection, such as satellite pictures in geographic information systems, are maintained in compressed form. Instead of performing a spatially selective operation on an image by first decompressing the compressed version, we propose in this paper to perform queries directly on the compressed version of the image. We suggest a compression technique that allows for the subsequent use of a spatial index structure to guide a spatial search. In response to a window query, our algorithm delivers a compressed partial image, or the exact uncompressed requested image region. In addition to the support of spatial queries on compressed continuous tone images, the new compression algorithm is even competitive in terms of the compression ratio that it achieves, compared to other standard lossless compression techniques. Index Terms---Lossless image comp...

This paper introduces Pica, a fine-grain, message passing architecture designed to efficiently support high-throughput parallel applications. This focus on high-throughput applications allows a small local memory of 4096 36-bit words. The architecture minimizes overhead for basic parallel operations. An operand-addressed context cache and round-robin task manager allow single cycle task swaps. Fixed-sized activation contexts simplify storage management. Word-tag synchronization bits provide low-cost synchronization. Several applications have been developed for this architecture including thermal relaxation, matrix multiplication, JPEG image compression, and positron emission tomography image reconstruction. These applications have been implemented and executed on the Pica architecture using an instrumented instruction-level simulator. Using these results, the architectural features of Pica are evaluated. 1 Introduction There are many approaches to exploiting fine-grain parallelism: in...

A multiresolution lossless image compression scheme based on several new tools will be presented in this paper. An improved multiresolution Haar transform will be developed, combined with pre- and post-processing and with a new entropy coder, to give the overall compression scheme. This research is mainly usedful for image compression in the medical imaging area, where changes between original and decompressed images are to be avoided. 1. INTRODUCTION Data compression is aimed at reducing storage and communication costs through the reduction of redundancy in the data representation.The most efficient compression techniques can achieve very important compression ratios but introduce losses in the decompressed in the decompressed image compared with the original one. Lossless compression gives lower compression ratios, but is crucial in applications such as medical imaging or satellite photography, where reliability of reproduction of images is a critical factor. Compression can be deco...