{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T17:27:43Z","timestamp":1777656463870,"version":"3.51.4"},"reference-count":26,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2015,3,10]],"date-time":"2015-03-10T00:00:00Z","timestamp":1425945600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>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.<\/jats:p>","DOI":"10.3390\/s150305747","type":"journal-article","created":{"date-parts":[[2015,3,10]],"date-time":"2015-03-10T10:59:09Z","timestamp":1425985149000},"page":"5747-5762","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":37,"title":["Sensor-Based Auto-Focusing System Using Multi-Scale Feature Extraction and Phase Correlation Matching"],"prefix":"10.3390","volume":"15","author":[{"given":"Jinbeum","family":"Jang","sequence":"first","affiliation":[{"name":"Image Processing and Intelligent System Laboratory Graduate School of Advanced Imaging Science, and Film Chung-Ang University, Seoul 156-756, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoonjong","family":"Yoo","sequence":"additional","affiliation":[{"name":"Image Processing and Intelligent System Laboratory Graduate School of Advanced Imaging Science, and Film Chung-Ang University, Seoul 156-756, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jongheon","family":"Kim","sequence":"additional","affiliation":[{"name":"Digital Design Team, SK Hynix, Gyeonggi-do 463-844, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8593-7155","authenticated-orcid":false,"given":"Joonki","family":"Paik","sequence":"additional","affiliation":[{"name":"Image Processing and Intelligent System Laboratory Graduate School of Advanced Imaging Science, and Film Chung-Ang University, Seoul 156-756, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,3,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Florea, C., and Florea, L. 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