Compressing images for the internet

Engineering Information Abstracts (Part I) when employed over bandwidth-limited, error-prone wireless channels. In this paper we propose an intuitive, low-complexity, pre-compression scheme that improves the performance of H.263 coded video over radio channels. In our scheme video frames are spatially segmented into regions of different perceptual importance before being compressed independently with the H.263 encoder. This allows us to apply unequal error protection and prioritized transmission to achieve at least a minimum temporal resolution at the receiver. Additionally, with this technique, both spatial and temporal error propagation is limited and through intra-frame statistical multiplexing the reserved transmission bandwidth is utilized optimally. Simulation results demonstrate that in the presence of severe error conditions and severe bandwidth constraints, our modified H.263 video codec exhibits better error concealment, better temporal resolution, and better bandwidth utilization properties than the original H.263 video codec. In English ŽAuthor abstract . 11 Refs. Keywords: Image coding; Image compression; Image communication systems; Radio communication; Communication channels Žinformation theory.; Image segmentation; Error analysis; Multiplexing; Bandwidth; Computer simulation; Constraint theory; Standards; Real time systems Title: COMPRESSING IMAGES FOR THE INTERNET Author(s): Beretta, Giordano Source: HP Laboratories Technical Report n 97-163 Dec 1997. Hwelett Packard Lab Technical Publ Dept Palo Alto CA USA. 11p CODEN: HLTREY Publication Year: 1997 Abstract: The World Wide Web has rapidly become the hot new mass communication medium. Content creators are using similar design and layout styles as in printed magazines, i.e., with many color images and graphics. The information is transmitted over plain telephone lines, where the speedrprice trade-off is much more severe than in the case of printed media. The standard design approach is to use palletized color and to limit as much as possible the number of colors used, so that the images can be encoded with a small number of bits per pixel using the Graphics Interchange Format ŽGIF. file format. The World Wide Web standards contemplate a second data encoding method ŽJPEG. that allows color fidelity but usually performs poorly on text, which is a critical element of information communicated on this medium. We analyze the spatial compression of color images and describe a methodology for using the JPEG method in a way that allows a compact representation while preserving full color fidelity. In English ŽAuthor abstract . 11 Refs. EI Order Number: 98024043333 Keywords: Image compression; Wide area networks; Image communication systems; Image coding; Color image processing; Color computer graphics; Telephone lines; Standards; Data structures Title: VISUAL INFORMATION RETRIEVAL FROM LARGE DISTRIBUTED ONLINE REPOSITORIES Author(s): Chang, Shih-Fu; Smith, John R.; Beigi, Mandis; Benitez, Ana

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Source: Communications of the ACM v 40 n 12 Dec 1997. ACM New York NY USA. p 63-71 ISSN: 0001-0782 CODEN: CACMA2 Corporate Source: Columbia Univ, New York, NY, USA Publication Year: 1997 Abstract: The potentials of search and retrieval from large, distributed, online visual information repositories is discussed and an Internet based system called WebSEEk and MetaSEEk is described. Visual information retrieval from these systems require the following critical components: a meta-data representation standard; open content-based query protocols; effective methods for summarizing visual information; further exploitation of query previewing techniques; exploration of both push and pull methods of progressive storage and retrieval of visual information; improved functionalities of the image and video representations; and methods of operating directly on compressed visual information. In English 12 Refs. EI Order Number: 98014033677 Keywords: Image communication systems; Information retrieval systems; Wide area networks; Query languages; Online systems; Digital image storage; Feature extraction; Interactive computer systems; Image compression; Standards; Online searching; Abstracting; Distributed computer systems

Title: VRML GETS REAL THE MPEG-4 WAY Author(s): Mulroy, Patrick Source: IEE Colloquium ŽDigest. Proceedings of the 1997 IEE Colloquium on Teleconferencing Futures Jun 17 1997 n 121 London, UK. IEE Stevenage England. p 4r1-4r4 ISSN: 0963-3308 CODEN: DCILDN Corporate Source: BT Lab, Ipswich, UK Publication Year: 1997 Abstract: As a standards effort with wide industry application, Moving Picture Expert Group-4 ŽMPEG. will make a significant impact on the multimedia world. MPEG-4 hopes to move multimedia communication from its current buzzword stage to being a real service on everyone’s desktop. The integration with the Virtual Reality Markup Language ŽVRML. world will add another dimension to this work and will make provision of enhanced telepresence and virtual meeting room technology far more likely in the near term. The hooks into the VRML 2.0 specification are already being discussed jointly by the VRML and MPEG-4 systems groups, and the core technology needed to develop the audiovisual coding and composition is already at an advanced stage. In English 7 Refs. EI Order Number: 98024080528 Keywords: Teleconferencing; Interactive computer systems; Standards; Virtual reality; Speech synthesis

Title: EXTENSIONS TO NONLINEAR EDITING ENCOMPASSING MPEG-2 4:2:2 PROFILE Author(s): Cornog, K.; Sporer, M. Source: Proceedings of the 1997 International Broadcasting Convention Sep 12-16 1997 n 447 Amsterdam, The Netherlands. IEE Stevenage Engl. p 302-307 ISSN: 0537-9989 CODEN: IECPB4