Parker, J.R.Jennings, C.Salkauskas, A.G.2008-05-082008-05-081993-02-01http://hdl.handle.net/1880/46426Most grey level thresholding methods produce good results in situations where the illumination gradient in the original raster image is regular and not too large. In other cases, such as a large linear change in illumination, a satisfactory bi-level image cannot be produced. If the object pixels can be identified in a variety of positions throughout the image, these can be used to construct a surface whose height is related to illumination at each pixel. This estimate can be used to produce a threshold for each pixel. The method described here uses the Shen-Castan edge detector to identify object pixels, and creates a surface using a moving least squares method that can be used to threshold the image.EngComputer Scienceunknown1993-506-1110.11575/PRISM/30959