This is an extension to another user’s question asking whether it is necessary to perform a Gaussian blur before using cv2.Canny(). I know from the documentation that cv2.HoughCircles() calls a Canny edge detector (presumably cv2.Canny()). Based on the user’s question, I need to use a Gaussian blur with the default Sobel kernel size. Does cv2.HoughCircles call cv2.Canny() with a default Sobel kernel size? If it does, does cv2.HoughCircles() method implicitly use a Gaussian blur already?

Thanks in advance!

CodePudding user response：

It does not perform Gaussian Blur.

It is recommended to apply Gaussian Blur before feeding your image to HoughCircles.

It also helps to smooth image a bit unless it's already soft. For example, GaussianBlur() with 7x7 kernel and 1.5x1.5 sigma or similar blurring may help.

In the current implementation of OpenCV there's no Gaussian Blur call.