Kernel for 3x3 Sobel horizontal edge detection filter (1st derivative approximation).
FilterSobelHorz3x3: TConvolutionFilter3x3 = ( Kernel: (( 1, 2, 1), ( 0, 0, 0), (-1, -2, -1)); Divisor: 1);
ImagingCanvases (at line 426)