Open AccessNoncontact and Wide-Field Characterization of the Absorption and Scattering Properties of Apple Fruit Using Spatial-Frequency Domain Imaging
Author(s) -
Dong Hu,
Xiaping Fu,
Xueming He,
Ying Yang
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep37920
Subject(s) - optics , spatial frequency , frequency domain , pixel , demodulation , characterization (materials science) , materials science , absorption (acoustics) , computer science , image resolution , scattering , computer vision , physics , telecommunications , channel (broadcasting)
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 (μ a ) 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 μ a and μwere 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 μ a and μ . The calculated μ a of apple tissue experiencing internal browning (IB) were much higher than healthy apple tissue, indicating that the SFDI technique had potential for IB tissue characterization.