Fill the holes in OpenCV [duplicate]

Question

I have an edge map extracted from edge detection module in OpenCV (canny edge detection). What I want to do is to fill the holes in the edge map.

I am using C++, and OpenCV libraries. In OpenCV there is a cvFloodFill() function, and it will fill the holes with a seed (with one of the location to start flooding). However, I am trying to fill all the interior holes without knowing the seeds.(similar to imfill() in MATLAB)

Q1: how to find all the seeds, so that I could apply 'cvFloodFill()'?
Q2: how to implement a 'imfill()' equivalent?

Newbie in OpenCV, and any hint is appreciated.

Answer 1

According to the documentation of imfill in MATLAB:

BW2 = imfill(BW,'holes'); 

fills holes in the binary image BW. A hole is a set of background pixels that cannot be reached by filling in the background from the edge of the image.

Therefore to get the "holes" pixels, make a call to cvFloodFill with the left corner pixel of the image as a seed. You get the holes by complementing the image obtained in the previous step.

MATLAB Example:

BW = im2bw( imread('coins.png') ); subplot(121), imshow(BW)  % used here as if it was cvFloodFill holes = imfill(BW, [1 1]);    % [1 1] is the starting location point  BW(~holes) = 1;               % fill holes subplot(122), imshow(BW)