Objective assessment and quantification of pearl quality by spectral-spatial features

Quality of pearl is subjectively and visually assessed by experts. The experts assess pearls from various factors such as size, shape, gloss, color, and so on. Among these factors, body color, interference color, glossiness and thickness of nacre of pearl are the most important for the quality of pearls. This study proposes a method that assesses and quantifies each factor of the pearl quality by using optical measurement. The spectral and spatial features were extracted from spectral imaging measurements. Quantitative values for each factor are estimated from the spectral and spatial features. We compared the estimated quantitative values with experts' evaluations. The result shows that the proposed method can accurately predict the experts' evaluations.