Skip to main content
ARS Home » Midwest Area » East Lansing, Michigan » Sugarbeet and Bean Research » Research » Publications at this Location » Publication #328181

Research Project: Nondestructive Quality Assessment and Grading of Fruits and Vegetables

Location: Sugarbeet and Bean Research

Title: Detection of fresh bruises in apples by structured-illumination reflectance imaging

item Lu, Renfu

Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: 3/23/2016
Publication Date: 5/20/2016
Citation: Lu, Y., Li, R., Lu, R. 2016. Detection of fresh bruises in apples by structured-illumination reflectance imaging. In: Proceedings of SPIE. Vol. 9864:986406.

Interpretive Summary:

Technical Abstract: Detection of fresh bruises in apples remains a challenging task due to the absence of visual symptoms and significant chemical alterations of fruit tissues during the initial stage after the fruit have been bruised. This paper reports on a new structured-illumination reflectance imaging (SIRI) technique for enhanced detection of fresh bruises in apples. Using a digital light projector engine, sinusoidally-modulated illumination at the spatial frequencies 50, 100, 150 and 200 cycles/m was generated, and a digital camera was then used to capture the reflectance images from ‘Gala’ and ‘Jonagold’ apples, immediately after they had been subjected to two levels of bruising by impact tests. A conventional three-phase demodulation (TPD) scheme was applied to the acquired images for obtaining the planar (direct component or DC) and amplitude (alternating component or AC) images. Furthermore, three spiral phase transform (SPT)-based demodulation methods, using single and two images and two phase-shifted images, were proposed for obtaining AC images. Results showed that the demodulation methods greatly enhanced the contrast and spatial resolution of the AC images, making it feasible to detect the fresh bruises that, otherwise, could not be achieved by conventional imaging technique with planar or uniform diffuse illumination. The effectiveness of image enhancement, however, varied with spatial frequency. Both 2-image and 2-phase SPT methods achieved good performance similar to that by TPD. SIRI technique was capable of detecting fresh bruises in apples, and it has the potential as a new imaging modality for enhancing food quality and safety detection.