【水到渠成C++】opencv基本操作 之 cv::MAt

1-获取图像尺寸、通道

cv::Mat src_rgba;
std::cout << "w: " << src_rgba.cols 
          << "h: " << src_rgba.rows 
          << "c: " << src_rgba.channels()
          << std::endl;

2-创建图像

cv::Mat img(INPUT_H, INPUT_W, CV_32F);  //有参构造
cv::Mat img;                            //无参构造
cv::Mat img = cv::imread("XXX.jpg");    //读图

3-归一化

（1）img/255-0

cv::Mat one;
img.convertTo(one, CV_32F, 1.0/255, 0);

（4）拆分

    cv::Mat img = cv::imread(argv[2]);    
    //2.拆分图片
    cv::Mat img_channels[3];
    split(img, img_channels);

    //3.区域图片混合
    cv::Mat img_blue = img_channels[0];
    cv::Mat img_gree = img_channels[1];
    cv::Mat img_red  = img_channels[2];

    cv::Mat one_img_blue;
    cv::Mat one_img_gree;
    cv::Mat one_img_red;
    img_blue.convertTo(one_img_blue, CV_32F, 1.0/58.395, -2.118);
    img_gree.convertTo(one_img_gree, CV_32F, 1.0/57.12, -2.036);
    img_red.convertTo(one_img_red, CV_32F, 1.0/57.375, -1.804);

    img_channels[0] = one_img_blue;
    img_channels[1] = one_img_gree;
    img_channels[2] = one_img_red;

     //4.图片组合
    cv::Mat img_merge;
    merge(img_channels, 3, img_merge);

（3）求范数

【详情】

void cv::normalize(InputArry src,
                InputOutputArray dst,
                double alpha=1,
                double beta=0,
                int norm_type=NORM_L2,
                int dtype=-1,
                InputArray mark=noArry())

4-查看图像元素

void showMat(cv::Mat &img){
    std::cout << "图像元素查看 ： " << img.rows<<"," << img.cols <(i, j)[0]<< ", " <<
                    (float)img.at(i, j)[1]<< ", " <<
                    (float)img.at(i, j)[2]<< ") " << std::endl;
                    //(int)img.at(i, j)[0]<< ", " <<
                    //(int)img.at(i, j)[1]<< ", " <<
                    //(int)img.at(i, j)[2]<< ") " << std::endl;
            }
        }
    }
}

5-图像缩放

6-图像裁剪