Enhancing colour differences in images of diseased mushrooms

Discoloration of mushrooms (senescence, damage, and bacterial infection) is an undesirable phenomenon in mushroom houses and on the market. Simple cluster analysis was not sufficient to discriminate the browning caused by disease from the natural browning of the mushroom. The transformation of RGB values to a* and b* colour components and the elimination of intensity gave a definitely better separation for the diseases. The best rate of separation was achieved by means of a vectorial normalisation, which was developed on the basis of the statistical analysis of the distribution of the colour points.