POCS-based blocking artifacts suppression using a smoothness constraint set with explicit region modeling

Alan Wee Chung Liew, Hong Yan, Ngai Fong Law

Research output: Journal article publicationJournal articleAcademic researchpeer-review

36 Citations (Scopus)


It is well known that low bit rate block-based discrete cosine transform coded image exhibits visually annoying coding artifacts. In this paper, we proposed a projection onto convex sets (PCOS)-based deblocking algorithm using a novel region smoothness constraint set for graphic images containing objects with smooth regions. The smoothness constraint set is obtained by an explicit modeling of smooth regions in the image using a spatially adaptive thin-plate spline. In contrast to most deblocking algorithms which enforce smoothness just around the 8 × 8 block boundaries, our algorithm enforces smoothness in regions which could possibly span several blocks. We showed that convergence of our algorithm could be reached within one iteration. The performance of the proposed algorithm is evaluated visually and quantitatively in term of peak signal-to-noise ratios and the mean squared difference of slope metric, which measures the impact of the blocking effects, for several graphic images. The results show that our algorithm can effectively suppress blockiness in smooth regions while still preserving the sharpness of object edges.
Original languageEnglish
Pages (from-to)795-800
Number of pages6
JournalIEEE Transactions on Circuits and Systems for Video Technology
Issue number6
Publication statusPublished - 1 Jun 2005


  • Blocking artifacts
  • Image deblocking
  • Projection onto convex sets (POCS)
  • Region smoothness constraint
  • Smooth surface modeling
  • Thin-plate spline

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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