Colour analysis of rice using flatbed scanning and image analysis

摘要

This paper describes a method for the determination of the colour of raw and processed rice using flatbed scanning (FBS) and image analysis (IA). Colour is one of the key quality attributes of rice and is influenced by processing. The colour of a bulk sample of rice was analysed by imaging a thick layer of rice on the scanner surface and measuring the average RGB colour. The RGB colours were converted to CIE L~*a~*b~* colours after calibration with rice samples measured by a colorimeter using the tristimulus XYZ values. For validation a separate set of rice samples was used. For the determination of the colour of individual rice kernels images were made of a single layer of rice spread on top of the glass plate of the FBS. The measured non-calibrated colour values can be used to detect specific kernels in a rice sample. The FBS method was also used for the determination of the amount of opaque or chalky rice kernels (chalkiness). The results of the determination of the chalkiness are comparable to those obtained by visual inspection using ISO 7301. The FBS-IA method is fast, easy to use and cheap. FBS-IA can monitor colour changes with the same accuracy and better precision than a colorimeter.