title: Noncontact and Wide-Field Characterization of the Absorption and Scattering Properties of Apple Fruit Using Spatial-Frequency Domain Imaging.
abstract: Spatial-frequency domain imaging (SFDI), as a noncontact, low-cost and wide-field optical imaging technique, offers great potential for agro-product safety and quality assessment through optical absorption (μa) and scattering (μ) property measurements. In this study, a laboratory-based SFDI system was constructed and developed for optical property measurement of fruits and vegetables. The system utilized a digital light projector to generate structured, periodic light patterns and illuminate test samples. The diffuse reflected light was captured by a charge coupled device (CCD) camera with the resolution of 1280 × 960 pixels. Three wavelengths (460, 527, and 630 nm) were selected for image acquisition using bandpass filters in the system. The μaand μ were calculated in a region of interest (ROI, 200 × 300 pixels) via nonlinear least-square fitting. Performance of the system was demonstrated through optical property measurement of 'Redstar' apples. Results showed that the system was able to acquire spatial-frequency domain images for demodulation and calculation of the μaand μ. The calculated μaof apple tissue experiencing internal browning (IB) were much higher than healthy apple tissue, indicating that the SFDI technique had potential for IB tissue characterization.
authors.affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Hu
authors.affiliation: Faculty of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, 928 Second Avenue, Xiasha Higher Education Zone, Hangzhou, 310018, China.
authors.forename: Xiaping
authors.initials: X
authors.lastname: Fu
authors.affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.
authors.forename: Xueming
authors.initials: X
authors.lastname: He
authors.affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.
authors.forename: Yibin
authors.initials: Y
authors.lastname: Ying
mesh_terms: D002138:Calibration; D004867:Equipment Design; D005638:Fruit / Q000737:chemistry / Q000502:physiology; D007091:Image Processing, Computer-Assisted / Q000379:methods; D027845:Malus / Q000737:chemistry* / Q000502:physiology*; D061848:Optical Imaging / Q000295:instrumentation / Q000379:methods*