Digital focus detector for mobile video communicators

Author

Kharitonenko, Igor ; Zhang, X.

Author_Institution

Motorola Australian Res. Centre, Botany, NSW, Australia

Volume

46

Issue

1

fYear

2000

fDate

2/1/2000 12:00:00 AM

Firstpage

233

Abstract

Theoretical analysis on digital focus detection has been conducted to uncover the underlying processes of auto focusing. According to this study, an optimal focus detector must employ an adaptive band pass filter, which takes into account both the input signal and the point spread function parameters. Focus detection efficiency of the commonly used squared gradient operator has been investigated. As shown, its performance can be essentially improved without introducing additional complexity. The modified detector is proved to be more robust, particularly operating in poor lighting conditions and has complexity acceptable for mobile imaging devices

Keywords

adaptive filters; adaptive signal detection; band-pass filters; focusing; gradient methods; mobile communication; optical transfer function; video equipment; video signal processing; visual communication; adaptive band pass filter; auto focusing; digital focus detector; digital image processing; focus detection efficiency; input signal; mobile imaging devices; mobile video communicators; modified detector; optimal focus detector; performance; point spread function parameters; poor lighting conditions; squared gradient operator; Filters;

fLanguage

English

Journal_Title

Consumer Electronics, IEEE Transactions on

Publisher

ieee

ISSN

0098-3063

Type

jour

DOI

10.1109/30.826404

Filename

826404