The parameter anchor of the function filter2D indicates the relative position of a filtered point within the kernel; But what is the detail of processing the value of the anchor?
For example：
The default value (-1,-1) means that the anchor is at the kernel center, but I think in this case the anchor.x and anchor.y are not equal to -1? What is the real value of the anchor? And how dose OpenCV process the value of the anchor?