Simple filter design for first and second order derivatives by a double filtering approach ?
We show how to compute image derivatives using fitted splines. Trigonometric splines are more exact than cubic splines using kernels of length 4. Double filtering can be combined into a single kernel of length 7. Pre blurring can be incorporated using approximating splines. Matlab code is provided.
first and second order derivatives cubic and trigonometric splines convolution filters separable kernels