Extraction of grid patterns on stamped metal sheets usingmathematical morphology

摘要

To validate models of sheet metal forming processes, experimentswith sheets of metal marked with grids are performed. A method formeasuring the deformed grid after processing is presented. It is basedon morphological image processing and it requires four steps. A largetop hat transformation is first applied to homogenize the grey levelintensities of the background. The two main directions of the grid arethen determined by calculating covariances. Linear filtering along thedirections of the grid is used to extract a mask of the grid pattern.This mask is then skeletonized in order to extract the medial axis ofthe grid as well as its intersection points