OpenCV皮肤检测

我一直在做一些皮肤检测，但不能得到一个光滑的。下图包含输入（左）和输出（右），使用下面的代码。现在，所需的输出应该是最底部的图像（边缘平滑，内部没有孔）。如何实现这个输出？

I've been doing some skin detection but can't get a smooth one. The image below contains the input (left) and output (right) using the code also attached below. Now, the desired output should have been the bottom most image (the one that is smooth on the edges and doesn't have holes within). How do I achieve this output? A sample code on where to start would be of great help.

输入（左）和输出不正确（右）：

Input (left) and Incorrect output (right):

>

想要的输出：

>

生成Incorect输出的代码：

Code to generate the Incorect output:

#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;

int main(){
    Mat src = imread("qq.jpg");
    if (src.empty())
        return -1;
    blur( src, src, Size(3,3) );
    Mat hsv;
    cvtColor(src, hsv, CV_BGR2HSV);
    Mat bw;
    inRange(hsv, Scalar(0, 10, 60), Scalar(20, 150, 255), bw);
    imshow("src", src);
    imshow("dst", bw);
    waitKey(0);
    return 0;
}

修改代码（Astor建议后）：
是：如何平滑输出？）

Modified Code (after Astor's suggestion): (the problem now is: how do you smoothen the output?)

#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;

int findBiggestContour(vector<vector<Point> >);

int main(){
    Mat src = imread("qq.jpg");
    if (src.empty())
        return -1;
    blur( src, src, Size(3,3) );

    Mat hsv;
    cvtColor(src, hsv, CV_BGR2HSV);

    Mat bw;
    inRange(hsv, Scalar(0, 10, 60), Scalar(20, 150, 255), bw);
    imshow("src", src);
    imshow("dst", bw);

    Mat canny_output;
    vector<vector<Point> > contours;
    vector<Vec4i> hierarchy;

    findContours( bw, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
    int s = findBiggestContour(contours);

    Mat drawing = Mat::zeros( src.size(), CV_8UC1 );
    drawContours( drawing, contours, s, Scalar(255), -1, 8, hierarchy, 0, Point() );

    imshow("drw", drawing);
    waitKey(0);
    return 0;
}

int findBiggestContour(vector<vector<Point> > contours){
    int indexOfBiggestContour = -1;
    int sizeOfBiggestContour = 0;
    for (int i = 0; i < contours.size(); i++){
        if(contours[i].size() > sizeOfBiggestContour){
            sizeOfBiggestContour = contours[i].size();
            indexOfBiggestContour = i;
        }
    }
    return indexOfBiggestContour;
}