Image Gradients

Note

When the size of the kernel is 3, the Sobel kernel shown above may produce noticeable inaccuracies (after all, Sobel is only an approximation of the derivative). OpenCV addresses this inaccuracy for kernels of size 3 by using the Scharr function. This is as fast but more accurate than the standar Sobel function. It implements the following kernels:

You can check out more information of this function in the OpenCV reference (Scharr). Also, in the sample code below, you will notice that above the code for Sobel function there is also code for the Scharr function commented. Uncommenting it (and obviously commenting the Sobel stuff) should give you an idea of how this function works.