I was learning about convolution and how filtering helps us to detect an edge in an image;however I still cannot not understand how the convolution process in the image below does this.
I understand how the last 4x4 matrix is created(the math operations);however I do not understand why the resultant matrix indicates that there is an edge in the image. In the resource it basically says : "If we interpret the matrix on the right as an image, there will be a lighter region (white) in the middle, that corresponds to the vertical edge detected in the center of an original 6×6 image." but it makes no sense for me why lighter region in the middle indicates vertical edge.