匹配模板IMGE（缩放）主/图片放大

Question

我想找/检查子图/模板图像在主图像，想知道它的坐标，我已经使用在以下链接来实现它定的代码

，

Check presence of subimage in image in iOS

它工作正常，如果模板图像的尺寸是较大的图像的匹配部分的大小完全相同。

但是，如果子图像缩小或放大比匹配较大图像的一部分，它不能正确给出结果。

Answer 1

使用OpenCV特征检测。它比模板匹配更精确..

请使用此代码尝试..

-(void)featureDetection:(UIImage*)largerImage withImage:(UIImage*)subImage 
{ 
    cv::Mat tempMat1 = [largerImage CVMat]; 
    cv::Mat tempMat2 = [subImage CVMat]; 

    cv::cvtColor(tempMat1, tempMat1, CV_RGB2GRAY); 
    cv::cvtColor(tempMat2, tempMat2, CV_RGB2GRAY); 

    if(!tempMat1.data || !tempMat2.data) { 
     return; 
    } 

    //-- Step 1: Detect the keypoints using SURF Detector 
    int minHessian = 25; 

    cv::SurfFeatureDetector detector(minHessian); // More Accurate bt take more time.. 
    //cv::FastFeatureDetector detector(minHessian); //Less Accurate bt take less time.. 

    std::vector<cv::KeyPoint> keypoints_1, keypoints_2; 

    detector.detect(tempMat1, keypoints_1); 
    detector.detect(tempMat2, keypoints_2); 

    //-- Step 2: Calculate descriptors (feature vectors) 
    cv::SurfDescriptorExtractor extractor; 

    cv::Mat descriptors_1, descriptors_2; 

    extractor.compute(tempMat1, keypoints_1, descriptors_1); 
    extractor.compute(tempMat2, keypoints_2, descriptors_2); 

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

    //Get the corners from the object 
    obj_corners[0] = (cvPoint(0,0)); 
    obj_corners[1] = (cvPoint(tempMat2.cols,0)); 
    obj_corners[2] = (cvPoint(tempMat2.cols,tempMat2.rows)); 
    obj_corners[3] = (cvPoint(0, tempMat2.rows)); 

    //-- Step 3: Matching descriptor vectors with a brute force matcher 
    //cv::BruteForceMatcher < cv::L2<float> > matcher; 
    cv::FlannBasedMatcher matcher; 
    //std::vector<cv::DMatch> matches; 
    std::vector<cv::vector<cv::DMatch > > matches; 

    std::vector<cv::DMatch > good_matches; 
    std::vector<cv::Point2f> obj; 
    std::vector<cv::Point2f> scene; 
    std::vector<cv::Point2f> scene_corners(4); 
    cv::Mat H; 

    matcher.knnMatch(descriptors_2, descriptors_1, matches,2); 

    for(int i = 0; i < cv::min(tempMat1.rows-1,(int) matches.size()); i++) { 

     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]); 
     } 
    } 
    cv::Mat img_matches; 
    drawMatches(tempMat2, keypoints_2, tempMat1, keypoints_1, good_matches, img_matches); 

    NSLog(@"good matches %lu",good_matches.size()); 

    if (good_matches.size() >= 4) { 

     for(int i = 0; i < good_matches.size(); i++) { 
      //Get the keypoints from the good matches 
      obj.push_back(keypoints_2[ good_matches[i].queryIdx ].pt); 
      scene.push_back(keypoints_1[ good_matches[i].trainIdx ].pt); 
     } 

     H = findHomography(obj, scene, CV_RANSAC); 

     perspectiveTransform(obj_corners, scene_corners, H); 

     NSLog(@"%f %f",scene_corners[0].x,scene_corners[0].y); 
     NSLog(@"%f %f",scene_corners[1].x,scene_corners[1].y); 
     NSLog(@"%f %f",scene_corners[2].x,scene_corners[2].y); 
     NSLog(@"%f %f",scene_corners[3].x,scene_corners[3].y); 


     //Draw lines between the corners (the mapped object in the scene image) 
     line(tempMat1, scene_corners[0], scene_corners[1], cvScalar(0, 255, 0), 4); 

     line(tempMat1, scene_corners[1], scene_corners[2], cvScalar(0, 255, 0), 4); 

     line(tempMat1, scene_corners[2], scene_corners[3], cvScalar(0, 255, 0), 4); 

     line(tempMat1, scene_corners[3], scene_corners[0], cvScalar(0, 255, 0), 4); 
    } 

    // View matching.. 

    UIImage *resultimage = [UIImage imageWithCVMat:img_matches]; 
    UIImageView *imageview = [[UIImageView alloc] initWithImage:resultimage]; 
    imageview.frame = CGRectMake(0, 0, 320, 240); 
    [self.view addSubview:imageview]; 

    // View Result 

    UIImage *resultimage2 = [UIImage imageWithCVMat:tempMat1]; 
    UIImageView *imageview2 = [[UIImageView alloc] initWithImage:resultimage2]; 
    imageview2.frame = CGRectMake(0, 240, 320, 240); 
    [self.view addSubview:imageview2]; 
}