During normal use of this kind of sorting machines in industry,changes caused by the evolution of the colour of the arils throughout the season require frequent re-training of the machine vision system. But these machines are usually handled by workers without any knowledge of computer vision or experience in statistics and they need a fast way to adapt the inspection software to the evolution of the colour of the product. Colour thresholds are intuitive and easy to implement by means of virtual switches in the graphical user interface. For this reason, this technique was one of the methods chosen for implementation in the prototype.