Train defected images, calculation of leaf area and defected area in a image

i have a collection of picturres of a an area which are mainly of soil and leaves. i have to first train some defect leaf by coding. Then i have to calculate those pictures from a folder through a code to calculate the area of good leaves and defected area of that image. my target is to calcul;ate the defect of leaves a certain region. Can any one help me in this sector by coding it?