The invention discloses an
image evaluation index establishing method for nondestructive diagnosis of
crop nitrogen nutrition. The method comprises the steps that wheat
canopy images and the
nitrogen content of leaves are obtained; the wheat
canopy images are subjected to partition extraction, average pixel values of R, G, B, H, S and I components of all non-zero pixel points of leaves in each wheat
canopy image are calculated to serve as basic color characteristic parameters r, g, b, h, s and i; nine image characteristic parameters r, g, b, r-g-b, r-g, r-b, (r-g-b) / (r+g+b), (r-g) / (r+g+b), and (r-b) / (r+g+b) are calculated; CMI=(xr-yg-zb) is established, fitting with the
nitrogen content of the leaves is carried out, weight coefficients x, y and z are determined, CMI is subjected to standardized
processing, and it is determined that NCMI=(xr-yg-zb) / (r+g+b). The NCMI established in the method is a relatively-proper
winter wheat nitrogen
nutrition evaluation index, accuracy and stability are achieved, and the
crop nitrogen content can be quantitatively evaluated.