TheAustrianCenterforParallelComputation(ACPC)isacooperativeresearch organization founded in 1989 to promote research and education in the eld of Software for Parallel Computer Systems. The areas in which the ACPC is active include algorithms, languages, c- pilers,programmingenvironments,andapplicationsforparallelandhigh-perf- mance computing systems. The partners of ACPC run researchprojects in these elds, use a common pool of hardware equipment, and oer a joint curriculum in ParallelComputationfor graduateand postgraduatestudents. Moreover,s- eral national and international workshops and conferences have been organized within the framework of the ACPC. TheseproceedingsconcerntheFourthInternationalConferenceoftheACPC (ACPC 99), held on February 16{18 in Salzburg, Austria. This conference is a merge of two established international conference/workshop series devoted to parallel processing: the ACPC conferences which were held previously in Salzburg, Gmunden, and Klagenfurt (all Austria) and the Parallel Numerics (ParNum) workshops which were organized in Smolenice (Slovakia), Sorrento (Italy), Gozd Martuljek (Slovenia), and Zakopane (Poland). We invited 20 researchers to participate on the program committee. The conference attracted authors from 22 countries around the worldwho submitted 75 papers, out of which 50 were selected for presentation at the conference. Additionally, a poster session was organized featuring work in progress. Four distinguished researcherspresented invited papers with topics related to the two specialtracksonParallelNumericsandParallelComputinginImageProcessing, Video Processing, and Multimedia.
