2D difference of offset Gaussian (DooG) filters. Creates a 2D derivative of Gaussian kernel. Use primarily for visualization purposes. For filtering better to use the indvidiual seperable kernels for efficiency purposes. INPUTS r - final mask will be 2r+1 x 2r+1 sigx - sigma for Gaussian in x direction sigy - sigma for Gaussian in y direction nderivs - order of derivative along each dimension show - [optional] figure to use for display (no display if == 0) OUTPUTS dG - The derivative of Gaussian mask EXAMPLE dG = filter_DOOG_2D( 20, 3, 3, [1,1], 1 ); DATESTAMP 29-Sep-2005 2:00pm See also FILTER_DOOG_1D, FILTER_DOOG_3D, FILTER_DOG_2D, FILTER_GABOR_2D