Enhanced autofocus algorithm using robust focus measure and fuzzy reasoning

Sang Yong Lee, Yogendera Kumar, Ji Man Cho, Sang Won Lee, Soo Won Kim

Research output: Contribution to journalArticlepeer-review

108 Citations (Scopus)


A new passive autofocus algorithm consisting of a robust focus measure for object detection and fuzzy reasoning for target selection is presented. The proposed algorithm first detects objects distributed in the image using a mid-frequency discrete cosine transform focus measure and then selects the target object through fuzzy reasoning with three fuzzy membership functions. The proposed algorithm is designed as full digital blocks and fabricated using 0.35-μm CMOS technology. Experimental results obtained from various samples show that the present method is insensitive to Gaussian and impulsive noises and able to improve the quality of the image by focusing to the appropriate target object.

Original languageEnglish
Article number4498431
Pages (from-to)1237-1246
Number of pages10
JournalIEEE Transactions on Circuits and Systems for Video Technology
Issue number9
Publication statusPublished - 2008 Sept

Bibliographical note

Funding Information:
Manuscript received November 17, 2006; revised September 19, 2007. First published April 30, 2008; current version published October 8, 2008. This work was supported by the Ministry of Information and Communication (MIC), Korea, under the IT Foreign Specialist Invitation Program (ITFSIP) supervised by the Institute of Information Technology Assessment (IITA) and Korea IT Industry Promotion Agency (KIPA). This paper was recommended by Associate Editor T. Fujii.


  • Autofocus (AF)
  • Focus measure
  • Fuzzy reasoning
  • Object detection

ASJC Scopus subject areas

  • Media Technology
  • Electrical and Electronic Engineering


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