Is it me or are the horizontal and verical Sobel kernels switched both in the ippi documentation and in the lib? The documented horizontal kernel is a vertical kernel and vice versa. Is thisa type of bug/oversight that will be corrected in future versions?
Vertical and horizontal Sobel functions are called because of their vertical and horizontal rows in their kernels. So "vertical" Sobel calculates dx and "horizontal" Sobel calculates dy.
Another feature is that ippiFilterSobelVert functions calculate -dx, not dx
You could use fixed filters "with border" that have "Border" suffix in the name. They do not require border pixels in memory. Also there is
ippiFilterSobelNegVertBorderfunction that calculates dx