A method of discriminating between kernel and chaff particles, in crop, using a crop viewing apparatus that includes: a) an image-capturing device that is capable of capturing one or more images, each comprising a plurality of pixels, of crop in the crop viewing apparatus, the image capturing device being operatively connected to an image processing device for processing one or more resulting images; b) one or more lamps 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 being an illumination intensity level at a chosen wavelength above which no substantial changes in reflectivity are observable; and c) one or more control devices for controlling the level of illumination provided by each said lamp, the method comprising the steps of d) operating at least one of said one or more control devices to cause illumination of crop in the crop viewing apparatus at one or more level less than the said reflectivity saturation level so as to enhance differences in reflectivity between kernels and chaff in the crop viewing apparatus; e) operating the image-capturing device while the crop is so illuminated to capture one or more crop images; and f) operating said image processing device and a programmable device in order to discriminate in the image between kernel and chaff particles based on their reflectivity characteristics at a said illumination level less than the saturation level, wherein the programmable device establishes the reflectivity as the ratio of the absolute reflection intensity by the kernels or chaff to the mean absolute reflection intensity of an entire captured image. a) an image-capturing device that is capable of capturing one or more images, each comprising a plurality of pixels, of crop in the crop viewing apparatus, the image capturing device being operatively connected to an image processing device for processing one or more resulting images; b) one or more lamps 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 being an illumination intensity level at a chosen wavelength above which no substantial changes in reflectivity are observable; and c) one or more control devices for controlling the level of illumination provided by each said lamp, the method comprising the steps of d) operating at least one of said one or more control devices to cause illumination of crop in the crop viewing apparatus at one or more level less than the said reflectivity saturation level so as to enhance differences in reflectivity between kernels and chaff in the crop viewing apparatus; e) operating the image-capturing device while the crop is so illuminated to capture one or more crop images; and f) operating said image processing device and a programmable device in order to discriminate in the image between kernel and chaff particles based on their reflectivity characteristics at a said illumination level less than the saturation level, wherein the programmable device establishes the reflectivity as the ratio of the absolute reflection intensity by the kernels or chaff to the mean absolute reflection intensity of an entire captured image.