A method of discriminating between kernel and chaff particles, in crop, using a crop viewing apparatus that includes:a) an image-capturing device (10) that is capable of capturing one or more images of crop in the crop viewing apparatus, the image capturing device being operatively connected to a processing device for processing one or more resulting imagesb) one or more lamps (23) for illuminating crop in the crop viewing apparatus, the or each said lamp being capable of illuminating the crop in a range of illumination levels up to a maximal level equal to or above a reflectivity saturation level at which increasing illumination causes no further reflectivity change andc) one or more control devices for controlling the level of illumination provided by each said lamp,the method comprising the steps ofd) operating at least one said control device to cause illumination of crop in the crop viewing apparatus at more level less than the said reflectivity saturation level so as to enhance differences in reflectivity between kernels and chaff in the crop viewing apparatuse) operating the image-capturing device while the crop is so illuminated to capture one or more crop images andf) operating one or more image processing devices in order to discriminate in the images between kernel and chaff particles based on their reflectivity characteristics at a said illumination level less than the saturation level.
