Patent ID: 6259827
Filing Date: 2001-07-10
Classification: G06T

Abstract:
A machine vision method for inspecting an object, comprising the steps of:illuminating the object with an illumination source selected from a group of illumination sources including (i) a direct on-axis light source that illuminates the object with direct illumination along a direction of a first axis, and (ii) a diffuse off-axis light source that illuminates the object with diffuse illumination at a grazing angle, and generating a first on-axis image of the object with an image capture device while the object is so illuminated, the image capture device being oriented for capturing the first on-axis image in the direction of the first axis;illuminating the object with another illumination source selected from the aforesaid group, and generating a second on-axis image of the object with the image capture device while it is so illuminated, the image capture device being oriented for capturing the second on-axis image in the direction of the first axis; andsubtracting the second image from the first image to form a third image that increases a contrast between the object and a background thereof.