Trying to Detect Circle with Houghcircles in OpenCV

Question

I am trying to detect circles in OpenCV using the method Houghcircles but when I am trying to run my code I get the following error:

Traceback (most recent call last):
  File "detect_circles.py", line 19, in <module>
    circles = cv2.cv.HoughCircles(gray, cv2.cv.CV_HOUGH_GRADIENT, 1.2, 100)
AttributeError: 'module' object has no attribute 'cv'

I am currently following the tutorial from this website: http://www.pyimagesearch.com/2014/07/21/detecting-circles-images-using-opencv-hough-circles/

I was wondering what was causing this error and what I could do to fix it.

I am running the code like this:

python detect_circles.py --image images/simple.png

And this is my code:

# import the necessary packages
import numpy as np
import argparse
import cv2
import copy

# construct the argument parser and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required = True, help = "Path to the image")
args = vars(ap.parse_args())

# load the image, clone it for output, and then convert it to grayscale
image = cv2.imread(args["image"])
original_img = cv2.imread(args["image"])
clone_img = copy.copy(original_img)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# detect circles in the image
circles = cv2.cv.HoughCircles(gray, cv2.cv.CV_HOUGH_GRADIENT, 1.2, 100)

# ensure at least some circles were found
if circles is not None:
    # convert the (x, y) coordinates and radius of the circles to integers
    circles = np.round(circles[0, :]).astype("int")

    # loop over the (x, y) coordinates and radius of the circles
    for (x, y, r) in circles:
        # draw the circle in the output image, then draw a rectangle
        # corresponding to the center of the circle
        cv2.circle(output, (x, y), r, (0, 255, 0), 4)
        cv2.rectangle(output, (x - 5, y - 5), (x + 5, y + 5), (0, 128, 255), -1)

    # show the output image
    cv2.imshow("output", np.hstack([image, output]))
    cv2.waitKey(0)

Answer 1

cv2.cv.HoughCircles(gray, cv2.cv.CV_HOUGH_GRADIENT, 1.2, 100)

The error message says it all. You have a typo in your code, the method should be called without the second cv module specifier.

cv2.HoughCircles(gray, cv2.HOUGH_GRADIENT, 1.2, 100)