Patent ID: 6532310
Filing Date: 2003-03-11
Classification: G06T

Abstract:
A method for measuring a physical feature of an object by accurately determining a position of an edge of the feature in a digitized image of at least a portion of the object, comprising:locating an approximate position of the edge; providing digitized image data corresponding to a selected area of the object which encompasses said approximate position of the edge and having respective values of an imaging parameter for pixels within said area; deriving an array of mÃ—n imaging parameter values corresponding to pixels arranged in a plurality of columns n each of which is spaced from said approximate position of the edge by a specified distance; setting a range of acceptable values of said imaging parameter; replacing all values of said imaging parameter in said array that are outside said range with a designated value to obtain a revised array of imaging parameter values; and accurately determining said position of the edge from said imaging parameter values in the revised array; wherein setting a range of acceptable values of said imaging parameter comprises: for each of columns n, deriving a distribution of the number of pixels vs. imaging parameter values; and based on the distribution, setting said range of acceptable values of the imaging parameter.