CODEWITHSUNDEEP
pythonopencvimage-processing
mluerig
mluerig

Reputation: 749

In opencv's findContours, what does cv.RETR_FLOODFILL do?

In the opencv documentation it says:

If mode equals to RETR_CCOMP or RETR_FLOODFILL, the input can also be a 32-bit integer image of labels (CV_32SC1).

After sending a converted image to the function, I got 180k contours, resulting the black mess below, if I plot them. So what does RETR_FLOODFILL do and how do I use it correctly?

img = cv2.imread("lena.png")
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
_, contours, _ = cv2.findContours(image=np.array(img, dtype=np.int32),  mode=cv2.RETR_FLOODFILL, method=cv2.CHAIN_APPROX_SIMPLE)
len(contours)
Out[7]: 183295

enter image description here

Upvotes: 6

Views: 6484

Answers (1)

MeiH
MeiH

Reputation: 1855

I think it does whatever function cv2.floodFill does. Finds all the pixels that are:

1-connected to each other

2-have intensity values close to each other

and consider them as a connected component. For example In your sample image, you have 183295 groups of pixels that are stick together and have a close intensity.

Upvotes: 3

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