在opencv中获取灰度图像的最大像素值

Question

我做了一些图像处理，并应用蒙版，我得到了我想要的。我可以清楚地看到，在"裁剪"的不显示结果中，图像中间有灰色像素。我试图获得最大像素值的位置。我检查了crop.channels()，它返回1。

    Mat mask = drawing2;
    drawContours(mask, contours, -1, Scalar(255), CV_FILLED);
    Mat dist;
    distanceTransform( cannyInv, dist, CV_DIST_L2, 3 );
    normalize(dist,dist,0.0,1.0,NORM_MINMAX);
    Mat crop;
    dist.copyTo(crop, mask);
    cout << "max.. "<< *std::max_element(crop.begin<double>(),crop.end<double>()) <<endl;

返回max..4.25593 e-08

    for(int y = 0; y < crop.rows; y++)
    {
        for(int x = 0; x < crop.cols; x++)
        {
            if (crop.at<unsigned char>(x,y) > 0){      
                cout << "X........"<<x<<" Y......"<<y<< " = "<<crop.at<unsigned char>(x,y) <<endl;
            }
        }
    }

输出为:

X........604 Y......479 = ¿
X........607 Y......479 =   
X........610 Y......479 = ¿

请帮帮我

PD:我知道也有类似的问题。但这是一个特殊的问题

Answer 1

我不知道我是怎么解决的。很多时间过去了。但是我现在的代码是这样的

    Mat dist=Mat::zeros(480,640, CV_8UC1);;
    distanceTransform( cannyInv, dist, CV_DIST_L2, 3 );
    Mat distNorm;
    dist.convertTo(distNorm, CV_8UC1,1,0);
    Mat result= Mat::zeros(480,640, CV_8UC1);
    distNorm.copyTo(result, mask);
    Mat tmp=Mat::zeros(480,640, CV_8UC1);
    Mat fik=Mat::zeros(480,640, CV_8UC3);
    for(int i = 0; i < result.rows; i++)
    {
        for(int j = 0; j < result.cols; j++)
        {
            if ( result.at< uchar >( i,j ) > 0){
                uchar val = result.at< uchar >( i,j  );
                if(val>maxVal){
                    if(val>0){
                        cv::circle(tmp,cvPoint(j,i),2,255,-1);
                    }
                    maxVal=val;
                    maxX = j;
                    maxY = i;
                }
            }
        }
    }

Answer 2

您确定规范化Mat会自动将其从uchar转换为double吗?很有可能数据仍然以字符的形式存储，而你从中读取了错误的数字。

尝试dist. convertto (dist, CV_64F);将数字以双精度输出

Answer 3

试试下面的代码:

cout << "X........"
     << x
     << " Y......"
     << y
     << " = "
     << (double) crop.at< unsigned char>(x,y) <<endl;