ellipse detection in opencv python

Question

My image is here:

i\'m looking for a better solution or algorithm to detect the

Answer 1

APPROACH 1:

As suggested by Miki, I was able to detect the ellipse in the given image using contour properties (in this I used the area property).

CODE:

#--- First obtain the threshold using the greyscale image ---
ret,th = cv2.threshold(gray,127,255, 0)

#--- Find all the contours in the binary image ---
_, contours,hierarchy = cv2.findContours(th,2,1)
cnt = contours
big_contour = []
max = 0
for i in cnt:
   area = cv2.contourArea(i) #--- find the contour having biggest area ---
    if(area > max):
        max = area
        big_contour = i 

final = cv2.drawContours(img, big_contour, -1, (0,255,0), 3)
cv2.imshow('final', final)

This is what I obtained:

APPROACH 2:

You can also use the approach suggested by you in this case. Hough detection of ellipse/circle.

You have to pre-process the image. I performed adaptive threshold and obtained this:

Now you can perform Hough circle detection on this image.

Hope it is not a mouthful!! :D