Colour analysis and the classification of fruit

Includes bibliography.The increasing high standards of fruit quality expected by the agricultural export market of South Africa has reached a stage that fruit must be accurately graded in a short a time as possible. This thesis describes colour systems and methods to grade the fruit automatically via the clustering and classification methods. After investigating several approaches to automatically sort fruit based on colour, an image processing approach was taken. The colours on the fruit (specifically apples) were analyzed, by capturing a colour image of the fruit and analyzing the pixels in the image. Several colour representation systems were investigated and they are: colours represented by spectral power distributions and spectral reflectance curves; the CIE 1931 XYZ tristimulus values; the CIE 1931 x ,y ,z chromaticity coordinates; the CIE 1960 L, u, v uniform chromaticity scale (UCS); the Munsell colour wheel of hue, value and chroma (HVC); the L*u*v* system; the L *a*b* system; the Red, Green and Blue (RGB) system; and the hue, saturation and intensity (HSI) perceptual colour representations. In addition, several clustering and classification techniques were investigated and they are: the supervised methods of Parametric Bayesian classification and minimum Euclidean distance classification; and the unsupervised methods of the K-means algorithm and the ISODATA classification approach. The ICS Texicon computer spectrophotometer (ICS Texicon Spectraflash Manual (1991)) was used to check the performance of most of the colour systems described by analyzing apple sample colour