如何在图像中定位对象？

Question

我有一个包含一组对象的黑白图像。 我希望能够找到这些对象。 我几乎可以肯定图像中的对象大小和形状几乎完全相同。

一种方法是在图像中逐个移动图像中的对象，直到我在图像中的像素与样本对象中的像素之间得到合理的匹配。 我可以为此编写自己的代码，但我宁愿不重新发明轮子。 AForge或EMGU / OpenCV中有没有这样做呢？

Answer 1

您可以使用openCV的Match模板功能。 此函数采用模板“您的对象集”，并将它们与您认为相同对象所在的图像进行比较。

链接到关于matchtemplate的opencv文档

Answer 2

你在openCV中有matchTemplate基本上就是你所说的。

Answer 3

你应该使用匹配，拿这个示例代码：

// Object_Matching_surf.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <opencv2/nonfree/features2d.hpp>
using namespace cv;
#include <stdio.h>
#include "stdafx.h"
#include <iostream>
#include"cv.h"
#include"highgui.h"
#include "opencv2/core/core.hpp"
#include "opencv2/features2d/features2d.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/calib3d/calib3d.hpp"

using namespace cv;

int object_detection(Mat, Mat, char*);
Mat rotateImage(const Mat&, double);
int main()
{
    char inputImgName[50];
    char tmplateName[50];
    char outputImgName[50];

    for (int i=1; i<10; i++)
    {
        sprintf(inputImgName, "%s%d%s","C:/Matches1/img",i,".png");
        sprintf(tmplateName, "%s%d%s","C:/Matches1/gripper",i,".png");
        sprintf(outputImgName, "%s%d%s","C:/Matches1/matches_img",i,".png");


    Mat templateImage = imread(tmplateName);//, CV_LOAD_IMAGE_GRAYSCALE );

    Mat inputImage = imread(inputImgName);//, CV_LOAD_IMAGE_GRAYSCALE );
    char * outPutImage = outputImgName;


    object_detection (templateImage, inputImage, outPutImage);

    }


    //Resize the template image
    /*Mat newTemlate;
    resize(templateImage,newTemlate, Size(100,100));*/

    //Rotate the template
    /*Mat rotatedTemplate  = rotateImage(templateImage, 90.0);
    imwrite("C:/Matches0/rotated.jpg" ,rotatedTemplate);*/

    return 0;
}

int object_detection(Mat templateImage, Mat inputImage, char* outPutImage)
{
    //Detect the keypoints using SURF Detector
    int minHessian = 500;

    SiftFeatureDetector detector( minHessian );
    std::vector<KeyPoint> kp_object;

    detector.detect( templateImage, kp_object );

    //Calculate descriptors (feature vectors)
    SiftDescriptorExtractor extractor;
    Mat des_object;

    extractor.compute( templateImage, kp_object, des_object );

    FlannBasedMatcher matcher;

    std::vector<Point2f> obj_corners(4);

    //Get the corners from the object
    obj_corners[0] = cvPoint(0,0);
    obj_corners[1] = cvPoint( templateImage.cols, 0 );
    obj_corners[2] = cvPoint( templateImage.cols, templateImage.rows );
    obj_corners[3] = cvPoint( 0, templateImage.rows );

        Mat des_image, img_matches;
        std::vector<KeyPoint> kp_image;
        std::vector<vector<DMatch > > matches;
        std::vector<DMatch > good_matches;
        std::vector<Point2f> obj;
        std::vector<Point2f> scene;
        std::vector<Point2f> scene_corners(4);
        Mat H;

        detector.detect( inputImage, kp_image );
        extractor.compute( inputImage, kp_image, des_image );

        matcher.knnMatch(des_object, des_image, matches, 2);

        for(int i = 0; i < min(des_image.rows-1,(int) matches.size()); i++) //THIS LOOP IS SENSITIVE TO SEGFAULTS
        {
            if((matches[i][0].distance < 0.6*(matches[i][1].distance)) && ((int) matches[i].size()<=2 && (int) matches[i].size()>0))
            {
                good_matches.push_back(matches[i][0]);
            }
        }

        //Draw only "good" matches
        drawMatches( templateImage, kp_object, inputImage, kp_image, good_matches, img_matches, Scalar::all(-1), Scalar::all(-1), vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

        if (good_matches.size() >= 4)
        {
            for( int i = 0; i < good_matches.size(); i++ )
            {
                //Get the keypoints from the good matches
                obj.push_back( kp_object[ good_matches[i].queryIdx ].pt );
                scene.push_back( kp_image[ good_matches[i].trainIdx ].pt );
            }

            H = findHomography( obj, scene, CV_RANSAC );

            perspectiveTransform( obj_corners, scene_corners, H);

            //Draw lines between the corners (the mapped object in the scene image )
            line( img_matches, scene_corners[0] + Point2f( templateImage.cols, 0), scene_corners[1] + Point2f( templateImage.cols, 0), Scalar(0, 255, 0), 4 );
            line( img_matches, scene_corners[1] + Point2f( templateImage.cols, 0), scene_corners[2] + Point2f( templateImage.cols, 0), Scalar( 0, 255, 0), 4 );
            line( img_matches, scene_corners[2] + Point2f( templateImage.cols, 0), scene_corners[3] + Point2f( templateImage.cols, 0), Scalar( 0, 255, 0), 4 );
            line( img_matches, scene_corners[3] + Point2f( templateImage.cols, 0), scene_corners[0] + Point2f( templateImage.cols, 0), Scalar( 0, 255, 0), 4 );
        }

        //Computing the center
        Point2f p1 = scene_corners[0] + Point2f( templateImage.cols, 0);
        Point2f p2 = scene_corners[1] + Point2f( templateImage.cols, 0);
        Point2f p3 = scene_corners[2] + Point2f( templateImage.cols, 0);
        Point2f p4 = scene_corners[3] + Point2f( templateImage.cols, 0);
        Point2f center = (p3*0.5+p1*0.5);

        char p1text[20];
        sprintf(p1text, "(%d,%d)",(int)p1.x, (int)p1.y );
        putText(img_matches, p1text, p1, FONT_HERSHEY_SIMPLEX, 0.3, cvScalar(255, 255, 255, 0));

        char p2text[20];
        sprintf(p2text, "(%d,%d)",(int)p2.x, (int)p2.y );
        putText(img_matches, p2text, p2, FONT_HERSHEY_SIMPLEX, 0.3, cvScalar(255, 255, 255, 0));

        char p3text[20];
        sprintf(p3text, "(%d,%d)",(int)p3.x, (int)p3.y );
        putText(img_matches, p3text, p3, FONT_HERSHEY_SIMPLEX, 0.3, cvScalar(255, 255, 255, 0));

        char p4text[20];
        sprintf(p4text, "(%d,%d)",(int)p4.x, (int)p4.y );
        putText(img_matches, p4text, p4, FONT_HERSHEY_SIMPLEX, 0.3, cvScalar(255, 255, 255, 0));

        char centertext[20];
        sprintf(centertext, "(%d,%d)",(int)center.x, (int)center.y );
        putText(img_matches, centertext, center, FONT_HERSHEY_SIMPLEX, 0.3, cvScalar(255, 0, 0, 250));

        system("pause");

        /* Save the image of matches */
        imwrite(outPutImage, img_matches);

    return 0;
}