• 使用OpenCV函數(shù) convexHull

步驟

1. 濾波——消除噪聲
2. 增強(qiáng)——二值化，使輪廓更明顯
3. 檢測(cè)——選出邊緣點(diǎn)
4. 計(jì)算凸包

例程

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <opencv2/highgui/highgui_c.h>
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace cv;
using namespace std;

Mat src; Mat src_gray;
int thresh = 100;
int max_thresh = 255;
RNG rng(12345);

/// Function header
void thresh_callback(int, void*);

/** @function main */
int main(int argc, char** argv)
{
    /// 加載源圖像
    src = imread("../images/hands2.jpg");

    /// 轉(zhuǎn)成灰度圖并進(jìn)行模糊降噪
    cvtColor(src, src_gray, CV_BGR2GRAY);
    blur(src_gray, src_gray, Size(3, 3));

    /// 創(chuàng)建窗體
    const char* source_window = "Source";
    namedWindow(source_window, CV_WINDOW_AUTOSIZE);
    imshow(source_window, src);

    createTrackbar(" Threshold:", "Source", &thresh, max_thresh, thresh_callback);
    thresh_callback(0, 0);

    waitKey(0);
    return(0);
}

/** @function thresh_callback */
void thresh_callback(int, void*)
{
    Mat src_copy = src.clone();
    Mat threshold_output;
    vector<vector<Point> > contours;
    vector<Vec4i> hierarchy;

    /// 對(duì)圖像進(jìn)行二值化
    threshold(src_gray, threshold_output, thresh, 255, THRESH_BINARY);

    /// 尋找輪廓
    findContours(threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));

    /// 對(duì)每個(gè)輪廓計(jì)算其凸包
    vector<vector<Point> >hull(contours.size());
    for (int i = 0; i < contours.size(); i++)
    {
        convexHull(Mat(contours[i]), hull[i], false);
    }

    /// 繪出輪廓及其凸包
    Mat drawing = Mat::zeros(threshold_output.size(), CV_8UC3);
    for (int i = 0; i < contours.size(); i++)
    {
        Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
        drawContours(drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point());
        drawContours(drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point());
    }

    /// 把結(jié)果顯示在窗體
    namedWindow("Hull demo", CV_WINDOW_AUTOSIZE);
    imshow("Hull demo", drawing);
}

這個(gè)手實(shí)在是太花哨了，必須得把閾值調(diào)得很大

這張顏色就很單一，閾值相對(duì)低很多