Patent ID: 8085987

Claim:
A method of evaluating texture of a surface, the method comprising: providing an image capturing device arranged to capture an image; providing a source of light arranged to project light in a lighting direction; locating the image capturing device along an orthogonal axis extending perpendicularly from the surface and facing the surface in a direction of the orthogonal axis so as to be arranged to capture an image of the surface; sequentially projecting light onto the surface from each of four light source positions spaced circumferentially about the orthogonal axis; arranging the lighting direction to be at a constant angle of inclination relative to the orthogonal axis in each of the four light source positions; arranging an intensity of the projected light to be constant in each of the four light source positions; capturing four images of the surface using the image capturing device in which the surface is illuminated by the light source from a respective one of the four lighting positions when each of the four images are captured; determining if a specularity condition exists in one of the four images by comparing intensities of the images directly with one another; if a specularity condition exists: i) determining three images of the four images which are least affected by specularity; and ii) determining a surface gradient of the surface using the three images.