Surface Gloss Measurement on Eggplant Fruit

Surface gloss is one of the important quality factors affecting consumer's opinion on purchasing eggplant fruits. The current manual gloss grading method is subject to human bias and the outcome is often very ambiguous. This study developed a sensing device consisting of two CCD monochrome cameras and three long tungsten lights and an associated quantitative method of measuring surface gloss of eggplant fruit using the device. Distinguishing various glossiness states of the fruit were made possible by analyzing the specular reflectance of the fruit surface. Specular reflection of the light on fruit surface was measured by digital image analysis method. Gradient filter was applied on the gray-level image for measuring magnitude of intensity changes. The algorithm consistency and validation test on the samples showed the algorithm was feasible of quantitatively assessing eggplant fruit surface gloss with an accuracy rate of 0.806. Details of the sensing devices, outline of the algorithm and preliminary results are presented in this article.