Use convolution with Sobel filters to compute the image gradient at each

pixel.

Args:

image$\_$bw: A numpy array of shape $($M$,$N$)$ containing the grayscale image

Returns:

Ix: Array of shape $($M$,$N$)$ representing partial derivatives of image

w$.$r$.$t$.$ x$-$direction

Iy: Array of shape $($M$,$N$)$ representing partial derivative of image

w$.$r$.$t$.$ y$-$direction