title: Focus measure based on the energy of high-frequency components in the S transform.
abstract: Focus measure plays a fundamental role in the shape from focus technique. In this Letter, we suggest a focus measure in the S-transform domain that is based on the energy of high-frequency components. A localized spectrum by using variable window size provides a more accurate method of measuring image sharpness as compared to other focus measures proposed in spectral domains. An optimal focus measure is obtained by selecting an appropriate frequency-dependent window width. The performance of the proposed focus measure is compared with those of existing focus measures in terms of three-dimensional shape recovery. Experimental results demonstrate the effectiveness of the proposed focus measure.
authors.affiliation: School of Information and Mechatronics, Gwangju Institute of Science and Technology, 261 Cheomdan Gwagiro,Buk-Gu, Gwangju 500-712, Korea.
authors.forename: Muhammad Tariq
authors.initials: MT
authors.lastname: Mahmood
authors.forename: Tae-Sun
authors.initials: TS
authors.lastname: Choi