Question

I have an image and I am using OpenCV to find the contours within that image. For example:

contours, hierarchy = cv2.findContours(image, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)

Each contour that get returned is sometimes very irregularly shaped. For example, the return of one of them is:

contour = [[[34  4]]
[[35  3]]
[[36  4]]
[[36 11]]
[[35 12]]
[[34 11]]
[[34  6]]
[[33  6]]
[[32  5]]
[[33  4]]]

I would like to set the interior of this contour to a specific color. I’ve tried using cv2.BoundingRect to get the bounding rectangle of this contour, and then using that to set the color, however, I would like a more precise way to do this using the actual contour.

Is there a straightforward way to do this through a function that OpenCV provides, or through NumPy?

Answer 1

Use cv2.drawContours() function with lineType = -1 flag (Docs)

eg : cv2.drawContours(img,[cnt],0,color,-1) # for filling inside a specific contour

or

cv2.drawContours(img,contours,-1,color,-1) # to fill inside all the contours in a single step

For more details, visit : Contours -1 : Getting Started