A POCS-based restoration algorithm for restoring halftoned color-quantized images

Yik Hing Fung, Yuk Hee Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

18 Citations (Scopus)


This paper studies the restoration of images which are color-quantized with error diffusion. Though there are many reported algorithms proposed for restoring noisy blurred color images and inverse halftoning, restoration of color-quantized images is rarely addressed in the literature especially when the images are color-quantized with halftoning. Direct application of existing restoration techniques are generally inadequate to deal with this problem. In this paper, a restoration algorithm based on projection onto convex sets is proposed. This algorithm makes use of the available color palette and the mechanism of a halftoning process to derive useful a priori information for restoration. Simulation results showed that it could improve the quality of a halftoned color-quantized image remarkably in terms of both SNR and CIELAB color difference metric.
Original languageEnglish
Pages (from-to)1985-1992
Number of pages8
JournalIEEE Transactions on Image Processing
Issue number7
Publication statusPublished - 1 Jul 2006


  • Color palette
  • Color quantization
  • Color restoration
  • Error diffusion
  • Image restoration
  • Inverse halftoning
  • Projection onto convex sets (POCS)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Computer Graphics and Computer-Aided Design
  • Software
  • Theoretical Computer Science
  • Computational Theory and Mathematics
  • Computer Vision and Pattern Recognition


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