Hi everyone. I want to fill a closed contour in C++. But I donot know how to fill it efficiently and correctly. Like the function imfill in matlab.
To fill a closed contour, you will need to
(1) Find a point which is inside the contour. This would be your seed point.
(2) Use a seed-fill algorithm. i.e., fill the 8-/4-connected area of the seed point. "imfill" in MATLAB does that.
Both (1) and (2) can easily be achieved using OpenCV functions. But I understand from your comment that you want to implement them from scratch.
For (1), check out http://en.wikipedia.org/wiki/Point_in_polygon (Peter has already mentioned one of the algorithms for this problem).
For (2), check out http://en.wikipedia.org/wiki/Flood_fill.
opencv C++ method cv::DrawControur with thickness as -1 is very efficient polygon filling algorithm.
To circumvent the seed(s) problem, you could do a reverse floodfill: assume the pixel in e.g. the upper-left corner is outside, use that corner as a seed for floodfill, and XOR the result.
Floodfill can be done recursively with an advancing front queue.
You can use the openCV library. There are a lot of methods that can help you.
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