Cereal Chem. 70:696-700   |  VIEW ARTICLE

Machine Recognition of Weevil Damage in Wheat Radiographs.

P. M. Keagy and T. F. Schatzki. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

An image processing algorithm was developed for machine recognition of weevils and/or weevil damage in digitally scanned film radiographs (8 bits, [0.25 mm][2]/pixel) of wheat kernels containing granary or maize weevils. The gray scale image is converted to a binary image of interior edges, lines, and cavities using a Laplacian mask, zero threshold, and background removal. In undamaged kernels, the predominant feature of this image is a line representing the central crease of the kernel. In insect-damaged kernels, this feature is disrupted, and additional edges or lines are seen at angles to the crease. The algorithm uses convolution masks to look for such intersections (45 or 90 degree angles with 4- or 5-pixel length sides) at eight orientations. Recognition varies with insect stage; at least 50% of infested kernels are machine recognized by the 4th instar (26-28 days). This is comparable to 50% recognition by humans at 25.5 days for images of similar resolution. False positive responses are limited to 0.5%.