Glare based apple sorting and iterative algorithm for bruise region detection using shortwave infrared hyperspectral imaging

Janos C. Keresztes, Elien Diels, Mohammad Goodarzi, Nghia Nguyen-Do-Trong, Peter Goos, Bart Nicolai, Wouter Saeys

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Bruises in apples is one of the most important quality factors during postharvest, which needs to be detected early and efficiently during sorting processes. In this study, a step-wise pixel based apple bruise detection system based on line scan hyperspectral imaging (HSI) in the shortwave infrared (SWIR) is demonstrated for three apple cultivars: ‘Jonagold’, ‘Kanzi’ and ‘Joly Red’. The SWIR HSI system performance was tested on apples from the different cultivars bruised at five different impact levels, and monitored from 1 to 36 h after bruising. While glare regions are commonly considered as anomalies and discarded from further analysis, their spectral signatures enabled in this work to distinguish between cultivars with a prediction accuracy up to 96%. Different partial least squares-discriminant analysis (PLS-DA) models were trained to discriminate cultivars and then to discriminate between sound, bruised, glossy and stem regions. Spectral area normalization pre-processing was found to be the most effective for pixel based bruise prediction, resulting in a prediction accuracy up to 90.1%. Post-processing of the binary images by exploiting spatial information further improved the bruise detection accuracy to 94.4%.

Original languageEnglish (US)
Pages (from-to)103-115
Number of pages13
JournalPostharvest Biology and Technology
Volume130
DOIs
StatePublished - Aug 1 2017

Keywords

  • Apple bruise detection
  • Fruit sorting
  • Glare
  • Joly Red
  • Jonagold
  • Kanzi
  • Specular reflection
  • SWIR hyperspectral imaging

ASJC Scopus subject areas

  • Food Science
  • Agronomy and Crop Science
  • Horticulture

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