user567879 user567879 - 1 month ago 13
Linux Question

cv2.hough circles error on video

When I run cv2.HoughCircles() I am getting the error

Traceback (most recent call last):
File "cv.py", line 1, in <module>
import cv2,cv
File "/home/jestinjoy/cv.py", line 19, in <module>
circles = np.uint16(np.around(circles))
File "/usr/lib/pymodules/python2.7/numpy/core/fromnumeric.py", line 2277, in around
return _wrapit(a, 'round', decimals, out)
File "/usr/lib/pymodules/python2.7/numpy/core/fromnumeric.py", line 37, in _wrapit
result = getattr(asarray(obj),method)(*args, **kwds)
AttributeError: rint


My code is

GNU nano 2.2.6 File: cv.py

import cv2,cv
import numpy as np

cv2.namedWindow("preview")
vc = cv2.VideoCapture(0)

if vc.isOpened(): # try to get the first frame
rval, frame = vc.read()
else:
rval = False

while rval:
cv2.imshow("preview", frame)
rval, frame = vc.read()
img = cv2.medianBlur(frame,5)
imgg = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
cimg = cv2.cvtColor(imgg,cv2.COLOR_GRAY2BGR)
circles = cv2.HoughCircles(imgg,cv2.cv.CV_HOUGH_GRADIENT,1,10,param1=100,param2=30,minRadius=5,maxRadius=20)
circles = np.uint16(np.around(circles))
for i in circles[0,:]:
cv2.circle(cimg,(i[0],i[1]),i[2],(0,255,0),1) # draw the outer circle
cv2.circle(cimg,(i[0],i[1]),2,(0,0,255),3) # draw the center of the circle
key = cv2.waitKey(20)
if key == 27: # exit on ESC
break
cv2.destroyWindow("preview")

Answer

you are not checking if you circles is None. If you do that, it works:

import cv2
import numpy as np

cv2.namedWindow("preview")
vc = cv2.VideoCapture(0)

if vc.isOpened(): # try to get the first frame
    rval, frame = vc.read()
else:
    rval = False

while rval:
        cv2.imshow("preview", frame)
        cv2.waitKey(1)
        rval, frame = vc.read()
        img = cv2.medianBlur(frame,5)
        imgg = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
        cimg = cv2.cvtColor(imgg,cv2.COLOR_GRAY2BGR)
        circles = cv2.HoughCircles(imgg,cv2.cv.CV_HOUGH_GRADIENT,1,10,param1=100,param2=30,minRadius=5,maxRadius=20)
        if circles is None:
                continue
        print circles
        #circles = np.uint16(np.around(circles))
        for i in circles[0,:]:
               cv2.circle(cimg,(i[0],i[1]),i[2],(0,255,0),1) # draw the outer circle
               cv2.circle(cimg,(i[0],i[1]),2,(0,0,255),3) # draw the center of the circle
        key = cv2.waitKey(20)
        if key == 27: # exit on ESC
                break
cv2.destroyWindow("preview")

Output generated:

sam@tuwien:/tmp$ python cv.py 
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
[[[ 335.5         368.5          10.12422848]]]
[[[ 334.5         386.5          10.12422848]]]
[[[ 349.5         382.5          10.12422848]]]
[[[ 392.5         365.5          10.12422848]]]
[[[ 378.5         370.5          10.12422848]]]
[[[ 378.5         368.5          12.34908867]]]
[[[ 391.5         369.5          14.57738018]]]
[[[ 379.5         370.5          10.12422848]]]
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