OpenCV using command line argument for input image (Python)

Question

I am trying to load an image from a file specified on the command line then process it using the OpenCV command HoughCircles. What happens is that I am opening the file:

img = cv2.imread(argv[0],0)

Then trying to use the following function:

def _getCircles(img):
  _circles = cv2.HoughCircles(img,cv2.cv.CV_HOUGH_GRADIENT,1,20,param1=50,param2=30,minRadius=1,maxRadius=20)

But returns the error:

cv2.error: error: (-206) Unrecognized or unsupported array type in function cvGetMat

However if I load the file directly ie change argv[0] to the explicit filename everything works perfectly. Any ideas?

Serdalis · Accepted Answer · 2013-09-12 01:14:07Z

6

In python and most other languages argv[0] contains the program name. Try using argv[1] to get the correct result.

Here is some Python Documentation to help you. Python has an amazing library of documentation I highly recommend using it.

answered Sep 12, 2013 at 1:14

Serdalis

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2 Comments

Matt Stokes Over a year ago

this is my fault for not explaining it right. I know about argv i was passing arguments from __main to def main(argv) via (sys.argv[1:]). Problem was silly using -t instead of -i for command line input. Technically your answer for the question I posed is correct but its my fault for not asking things properly

Serdalis Over a year ago

@MattStokes Shame I wasn't of use but I'm glad you found and fixed the problem anyway.

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