METHOD AND APPARATUS FOR INSPECTING SURFACES FOR CONTRAST VARIATIONS

A method of and apparatus for inspecting the surface of an article for isolated contrast variations by illuminating the surface, forming an image of the surface from the reflected light, the image being composed of pixels that contain digitized information indicative of the relative intensity level of light reflected from a particular portion of the surface, comparing the intensity levels of at least some of the pixels to a predetermined intensity threshold to identify portions of the surface contrasting with other portions of that surface, and determining from the identified pixels the number of isolated contrast variations on the surface and the area of each of the variations. The number and size of the contrast variations appearing on the inspected article surface are compared to acceptability criteria to decide whether the article is acceptable for a particular use or in particular channels of commerce.