samples/cpp/watershed.cpp

使用分水嶺演算法的示例

#include <opencv2/core/utility.hpp>
#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
 
#include <cstdio>
#include <iostream>
 
using namespace cv;
using namespace std;
 
static void help(char** argv)
{
cout << "\n此程式演示了 OpenCV 中著名的分水嶺分割演算法：watershed()\n"
            "用法:\n" << argv[0] <<" [image_name -- 預設為 fruits.jpg]\n" << endl;
 
 
cout << "熱鍵: \n"
        "\tESC - 退出程式\n"
        "\tr - 恢復原始影像\n"
        "\tw 或 空格 - 執行分水嶺分割演算法\n"
        "\t\t(在執行之前，*大致*標記影像上要分割的區域)\n"
        "\t (在此之前，在影像上大致勾勒出幾個標記)\n";
}
Mat markerMask, img;
Point prevPt(-1, -1);
 
static void onMouse( int event, int x, int y, int flags, void* )
{
    if( x < 0 || x >= img.cols || y < 0 || y >= img.rows )
        return;
    if( event == EVENT_LBUTTONUP || !(flags & EVENT_FLAG_LBUTTON) )
prevPt = Point(-1,-1);
    else if( event == EVENT_LBUTTONDOWN )
prevPt = Point(x,y);
    else if( event == EVENT_MOUSEMOVE && (flags & EVENT_FLAG_LBUTTON) )
    {
        Point pt(x, y);
        if( prevPt.x < 0 )
prevPt = pt;
line( markerMask, prevPt, pt, Scalar::all(255), 5, 8, 0 );
line( img, prevPt, pt, Scalar::all(255), 5, 8, 0 );
prevPt = pt;
imshow("image", img);
    }
}
 
int main( int argc, char** argv )
{
    cv::CommandLineParser parser(argc, argv, "{help h | | }{ @input | fruits.jpg | }");
    if (parser.has("help"))
    {
help(argv);
        return 0;
    }
    string filename = samples::findFile(parser.get<string>("@input"));
    Mat img0 = imread(filename, IMREAD_COLOR), imgGray;
 
    if( img0.empty() )
    {
cout << "無法開啟影像 ";
help(argv);
        return 0;
    }
help(argv);
    namedWindow( "image", 1 );
 
img0.copyTo(img);
    cvtColor(img, markerMask, COLOR_BGR2GRAY);
    cvtColor(markerMask, imgGray, COLOR_GRAY2BGR);
markerMask = Scalar::all(0);
    imshow( "image", img );
    setMouseCallback( "image", onMouse, 0 );
 
    for(;;)
    {
        char c = (char)waitKey(0);
 
        if( c == 27 )
            break;
 
        if( c == 'r' )
        {
markerMask = Scalar::all(0);
img0.copyTo(img);
            imshow( "image", img );
        }
 
        if( c == 'w' || c == ' ' )
        {
            int i, j, compCount = 0;
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
 
            findContours(markerMask, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE);
 
            if( contours.empty() )
                continue;
            Mat markers(markerMask.size(), CV_32S);
markers = Scalar::all(0);
            int idx = 0;
            for( ; idx >= 0; idx = hierarchy[idx][0], compCount++ )
                drawContours(markers, contours, idx, Scalar::all(compCount+1), -1, 8, hierarchy, INT_MAX);
 
            if( compCount == 0 )
                continue;
 
vector<Vec3b> colorTab;
            for( i = 0; i < compCount; i++ )
            {
                int b = theRNG().uniform(0, 255);
                int g = theRNG().uniform(0, 255);
                int r = theRNG().uniform(0, 255);
 
colorTab.push_back(Vec3b((uchar)b, (uchar)g, (uchar)r));
            }
 
            double t = (double)getTickCount();
            watershed( img0, markers );
t = (double)getTickCount() - t;
printf( "執行時間 = %gms\n", t*1000./getTickFrequency() );
 
            Mat wshed(markers.size(), CV_8UC3);
 
            // 繪製分水嶺影像
            for( i = 0; i < markers.rows; i++ )
                for( j = 0; j < markers.cols; j++ )
                {
                    int index = markers.at<int>(i,j);
                    if( index == -1 )
wshed.at<Vec3b>(i,j) = Vec3b(255,255,255);
                    else if( index <= 0 || index > compCount )
wshed.at<Vec3b>(i,j) = Vec3b(0,0,0);
                    else
wshed.at<Vec3b>(i,j) = colorTab[index - 1];
                }
 
wshed = wshed*0.5 + imgGray*0.5;
            imshow( "分水嶺變換", wshed );
        }
    }
 
    return 0;
}