this book constitutes the refereed proceedings of the 4th international conference on parallel computation, acpc99, held in salzburg, austria in february 1999; the conference included special tracks on parallel numerics and on parallel computing in image processing, video processing, and multimedia.the volume presents 50 revised full papers selected from a total of 75 submissions. also included are four invited papers and 15 posters. the papers are organized in topical sections on linear algebra, differential equations and interpolation, (quasi-)monte carlo methods, numerical software, numerical applications, image segmentation and image understanding, motion estimation and block matching, video processing, wavelet techniques, satellite image processing, data structures, data partitioning, resource allocation and performance analysis, cluster computing, and simulation and applications.