Image Processing Horizontal Prewitt Filtering Kernel Vertical Prewitt Filter The Vertical Prewitt operation acts like a gradient filter. This has the effect of highlighting ver- tical edges (gradients) in the image. The kernel size used is 3 and it is shown in the following figure. The absolute clipping method is usually used with this filtering operation. Vertical Prewitt Filtering Kernel Horizontal Sobel Filter The Horizontal Sobel operation acts like a gradient filter. This has the effect of highlighting horizontal edges (gradients) in the image. The kernel size can be 3, 5 or 7. The absolute clip- ping method is usually used with this filtering operation.
The kernels used by the Image Pro- cessing Tool are shown in the following figure. Horizontal Sobel Filtering Kernels ACEUser's Guide, 3.6.x, 18316-000 Rev A Page 516