Does cv2.Canny() perform a Gaussian blur?
The aperture argument of Canny controls the size of the Sobel filter (from 1 to 7 ?), which in fact applies a lowpass filter before taking the derivative. Unfortunately, the documentation is not explicit about that lowpass filter, though Gaussian is cited.
I bet that a binomial filter is in fact used (which is a close approximation to a Gaussian).
I know it's important to apply Gaussian blur to an image before using Canny to detect edges. My question is: does cv2.Canny() do Gaussian blur on its own or it is necessary to apply cv2.GaussianBlur() before cv2.Canny()? The documentation isn't clear on this point.