Algorithms pp 407-418 | Cite as

Parallel algorithms for labeling image components

  • Wen-Jing Hsu
  • Xiaola Lin
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 450)


We study the problem of labeling connected components of an N1/2×N1/2 image using parallel computers. The following new results are presented:
  1. 1).

    Based on the CRCW PRAM (Concurrent-Read Concurrent-Write Parallel Random Access Machine) model, we show that Θ(N/logN) processors are necessary and sufficient to solve the image component problem in O(logN) time. The best known algorithm uses N processors to achieve the same time bound.

  2. 2).

    We show that Θ(N/log2N) hypercube or shuffle processors are necessary and sufficient to solve the same problem in O(log2N) time. This new result improves the processor requirement of the best existing algorithm by a factor of O(log2N).

  3. 3).

    We present a new mesh computer algorithm aimed to improve the utilization of the processor resource while maintaining reasonable speedup over the sequential algorithm. The algorithm that is presented uses only O(N1/2) processors and executes in O(N1/2logN) time. This time complexity is a factor of O(logN) away from the optimal time complexity of O(N1/2); however, the number of processors is reduced by a factor of O(N1/2) from O(N).

  4. 4).

    We show that these algorithms can be extended to compute components in k-dimension and to compute components based on generalized connectivities.



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Copyright information

© Springer-Verlag Berlin Heidelberg 1990

Authors and Affiliations

  • Wen-Jing Hsu
    • 1
  • Xiaola Lin
    • 1
  1. 1.Department of Computer ScienceMichigan State UniversityEast Lansing

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