A system and method use 2D and 3D numerical gradient operators for reducing anisotropic inaccuracies in digital image processing. Enhanced isotropic operators are derived by first parameterizing corresponding numerical operators, followed by determining the parameters for the operators by matching analytical...http://www.google.com/patents/US7653258?utm_source=gb-gplus-sharePatent US7653258 - Enhanced isotropic 2D and 3D gradient method
