title: Sensor-based auto-focusing system using multi-scale feature extraction and phase correlation matching.
abstract: This paper presents a novel auto-focusing system based on a CMOS sensor containing pixels with different phases. Robust extraction of features in a severely defocused image is the fundamental problem of a phase-difference auto-focusing system. In order to solve this problem, a multi-resolution feature extraction algorithm is proposed. Given the extracted features, the proposed auto-focusing system can provide the ideal focusing position using phase correlation matching. The proposed auto-focusing (AF) algorithm consists of four steps: (i) acquisition of left and right images using AF points in the region-of-interest; (ii) feature extraction in the left image under low illumination and out-of-focus blur; (iii) the generation of two feature images using the phase difference between the left and right images; and (iv) estimation of the phase shifting vector using phase correlation matching. Since the proposed system accurately estimates the phase difference in the out-of-focus blurred image under low illumination, it can provide faster, more robust auto focusing than existing systems.
authors.affiliation: Image Processing and Intelligent System Laboratory Graduate School of Advanced Imaging Science, and Film Chung-Ang University, Seoul 156-756, Korea. jinbeum23@cau.ac.kr.
authors.forename: Jinbeum
authors.initials: J
authors.lastname: Jang
authors.affiliation: Image Processing and Intelligent System Laboratory Graduate School of Advanced Imaging Science, and Film Chung-Ang University, Seoul 156-756, Korea. whitener@cau.ac.kr.
authors.forename: Yoonjong
authors.initials: Y
authors.lastname: Yoo
authors.affiliation: Digital Design Team, SK Hynix, Gyeonggi-do 463-844, Korea. jongheon.kim@sk.com.
authors.forename: Jongheon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Image Processing and Intelligent System Laboratory Graduate School of Advanced Imaging Science, and Film Chung-Ang University, Seoul 156-756, Korea. paikj@cau.ac.kr.
authors.forename: Joonki
authors.initials: J
authors.lastname: Paik