Classification of Paddy Diseases Using Ellipse Fitting

Plant diseases are major threats to the agriculture sector which adversely affect the Indian economy. Correct identification of plant diseases is important for choosing preventive measures. Paddy is a widely consumed and cultivated food crop. Brown spot and leaf blast are two fungal diseases that affect paddy. There occurs a minor difference in the shape of the spots caused by these two diseases. Image processing techniques can be used to identify disease infected segments and calculate disease spread. The proposed system aims to classify brown spot and leaf blast diseases in paddy. It first segments the disease-affected region and calculates the disease spread in terms of area. Morphological operations enable the complete inclusion of the infected region by hole filling. The system is capable of detecting disease at a premature stage by detecting even mild infected spots. Then ellipse fitting is applied to the segmented images and the ratio of the length of the major axis to the minor axis is calculated. The ratio calculated for the two classes is used to define a threshold, which is used to classify the images. The system achieves 97% accuracy in classifying these two diseases.