This document discusses a technique for detecting plant leaf diseases using image processing. It begins with an introduction to plant pathology and the importance of identifying plant diseases. Common plant leaf diseases like Alternaria Alternata, Anthracnose, Bacterial blight, and Cercospora Leaf Spot are described along with their symptoms. The existing methods of disease identification are discussed. The proposed method uses various image processing techniques like filtering, histogram equalization, k-means clustering, and Gray Level Co-occurrence Matrix (GLCM) feature extraction to detect diseases. Image quality is then assessed to identify the affected regions of the leaf.