Sobel filter - cerr/CERR GitHub Wiki
Sobel filters are used to compute the magnitude and direction of the local gradient in 2-D.
The horizontal gradient (Gx) is approximated by the convolution of image 'I' with kernel Fx:
The vertical gradient (Gy is approximated by the convolution of image 'I' with kernel Fy:
The magnitude of the local gradient is computed as:
And its direction is given by:
- Sobel, I. (1990). An isotropic 3× 3 image gradient operator, Machine vision for three-dimensional scenes, 376-379.