Restoration of error-diffused images using projection onto convex sets

Gozde Bozkurt Unal*, A. Enis Çetin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


In this paper, a novel inverse halftoning method is proposed to restore a continuous tone image from a given half-tone image. A set theoretic formulation is used where three sets are defined using the prior information about the problem. A new space-domain projection is introduced assuming the halftoning is performed using error diffusion, and the error diffusion filter kernel is known. The space-domain, frequency-domain, and space-scale domain projections are used alternately to obtain a feasible solution for the inverse halftoning problem which does not have a unique solution.

Original languageEnglish
Pages (from-to)1836-1841
Number of pages6
JournalIEEE Transactions on Image Processing
Issue number12
Publication statusPublished - Dec 2001
Externally publishedYes


Manuscript received November 10, 1999; revised September 1, 2001. This work was supported in part by NATO under Grant CRG-971117 and was carried out at Bilkent University, Ankara, Turkey. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Timothy J. Schulz.

FundersFunder number
North Atlantic Treaty OrganizationCRG-971117


    • Error diffusion
    • Inverse error diffusion
    • Inverse halftoning
    • Projection onto convex sets (POCS)
    • Restoration


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