Compressing images for the internet

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  • ( )Engineering Information Abstracts Part I 405

    when employed over bandwidth-limited, error-prone wirelesschannels. In this paper we propose an intuitive, low-complex-ity, pre-compression scheme that improves the performance ofH.263 coded video over radio channels. In our scheme videoframes are spatially segmented into regions of different per-ceptual importance before being compressed independentlywith the H.263 encoder. This allows us to apply unequal errorprotection and prioritized transmission to achieve at least aminimum temporal resolution at the receiver. Additionally,with this technique, both spatial and temporal error propaga-tion is limited and through intra-frame statistical multiplexingthe reserved transmission bandwidth is utilized optimally.Simulation results demonstrate that in the presence of severeerror conditions and severe bandwidth constraints, our modi-ed H.263 video codec exhibits better error concealment,better temporal resolution, and better bandwidth utilizationproperties than the original H.263 video codec. In English .Author abstract 11 Refs.Keywords: Image coding; Image compression; Image commu-nication systems; Radio communication; Communication

    .channels information theory ; Image segmentation; Erroranalysis; Multiplexing; Bandwidth; Computer simulation; Con-straint theory; Standards; Real time systems

    Title: COMPRESSING IMAGES FOR THE INTERNET( )Author s : Beretta, Giordano

    Source: HP Laboratories Technical Report n 97-163 Dec1997. Hwelett Packard Lab Technical Publ Dept Palo Alto CAUSA. 11p CODEN: HLTREYPublication Year: 1997Abstract: The World Wide Web has rapidly become the hotnew mass communication medium. Content creators are usingsimilar design and layout styles as in printed magazines, i.e.,with many color images and graphics. The information istransmitted over plain telephone lines, where the speedrpricetrade-off is much more severe than in the case of printedmedia. The standard design approach is to use palletized colorand to limit as much as possible the number of colors used, sothat the images can be encoded with a small number of bits

    .per pixel using the Graphics Interchange Format GIF leformat. The World Wide Web standards contemplate a sec-

    .ond data encoding method JPEG that allows color delitybut usually performs poorly on text, which is a critical elementof information communicated on this medium. We analyze thespatial compression of color images and describe a method-ology for using the JPEG method in a way that allows acompact representation while preserving full color delity. In

    .English Author abstract 11 Refs. EI Order Number:98024043333Keywords: Image compression; Wide area networks; Imagecommunication systems; Image coding; Color image process-ing; Color computer graphics; Telephone lines; Standards;Data structures


    ( )Author s : Chang, Shih-Fu; Smith, John R.; Beigi, Mandis;Benitez, Ana

    Source: Communications of the ACM v 40 n 12 Dec 1997.ACM New York NY USA. p 63-71 ISSN: 0001-0782 CODEN:CACMA2Corporate Source: Columbia Univ, New York, NY, USAPublication Year: 1997Abstract: The potentials of search and retrieval from large,distributed, online visual information repositories is discussedand an Internet based system called WebSEEk and MetaSEEkis described. Visual information retrieval from these systemsrequire the following critical components: a meta-data repre-sentation standard; open content-based query protocols; ef-fective methods for summarizing visual information; furtherexploitation of query previewing techniques; exploration ofboth push and pull methods of progressive storage and re-trieval of visual information; improved functionalities of theimage and video representations; and methods of operatingdirectly on compressed visual information. In English 12 Refs.EI Order Number: 98014033677Keywords: Image communication systems; Information re-trieval systems; Wide area networks; Query languages; Onlinesystems; Digital image storage; Feature extraction; Interactivecomputer systems; Image compression; Standards; Onlinesearching; Abstracting; Distributed computer systems

    Title: VRML GETS REAL THE MPEG-4 WAY( )Author s : Mulroy, Patrick

    .Source: IEE Colloquium Digest Proceedings of the 1997IEE Colloquium on Teleconferencing Futures Jun 17 1997 n121 London, UK. IEE Stevenage England. p 4r1-4r4 ISSN:0963-3308 CODEN: DCILDNCorporate Source: BT Lab, Ipswich, UKPublication Year: 1997Abstract: As a standards effort with wide industry application,

    .Moving Picture Expert Group-4 MPEG will make a signi-cant impact on the multimedia world. MPEG-4 hopes to movemultimedia communication from its current buzzword stage tobeing a real service on everyone's desktop. The integration

    .with the Virtual Reality Markup Language VRML world willadd another dimension to this work and will make provision ofenhanced telepresence and virtual meeting room technologyfar more likely in the near term. The hooks into the VRML2.0 specication are already being discussed jointly by theVRML and MPEG-4 systems groups, and the core technologyneeded to develop the audiovisual coding and composition isalready at an advanced stage. In English 7 Refs. EI OrderNumber: 98024080528Keywords: Teleconferencing; Interactive computer systems;Standards; Virtual reality; Speech synthesis


    ( )Author s : Cornog, K.; Sporer, M.Source: Proceedings of the 1997 International BroadcastingConvention Sep 12-16 1997 n 447 Amsterdam, The Nether-lands. IEE Stevenage Engl. p 302-307 ISSN: 0537-9989CODEN: IECPB4