Abstract: The present application discloses a product inspection system or method having application for detecting defective product. In illustrated embodiments the system utilizes an input product image to detect defects in product. As disclosed, a vector generator creates a gray scale data vector representing a number of pixels having an associated gray scale value for the product image. A defect detector uses the gray scale data vector and a data store of gray scale vector clusters having an associated anomaly index to assign an anomaly value to the product image, which is used to provide an inspection output for the product image.