#include <opencv.hpp>

#include <vector>

using namespace std;

using namespace cv;

void creatAlphaMat(Mat &mat) // 创建一个图像

{

    for (int i = ; i < mat.rows; i++)

    {

        for (int j = ; j < mat.cols; j++)

        {

            Vec4b&rgba = mat.at<Vec4b>(i, j);

            rgba[] = UCHAR_MAX;

            rgba[] = saturate_cast<uchar>((float(mat.cols - j)) / ((float)mat.cols)*UCHAR_MAX);

            rgba[] = saturate_cast<uchar>((float(mat.rows - i)) / ((float)mat.rows)*UCHAR_MAX);

            rgba[] = saturate_cast<uchar>(0.5*(rgba[] + rgba[]));

        }

    }

}

int main()

{

    //创建带Alpha通道的 Mat

    Mat mat(, , CV_8UC4);

    creatAlphaMat(mat);

    vector<int>compression_params;

    compression_params.push_back(IMWRITE_PNG_COMPRESSION);

    compression_params.push_back();

    try{

        imwrite("透明值图.png", mat, compression_params);

        imshow("生成的PNG图", mat);

        fprintf(stdout, "PNG图片文件的数据保存完毕");

        waitKey();

    }

    catch (runtime_error& ex){

        fprintf(stderr, "图像转换发生错误:%s\n", ex.what());

        return ;

    }

    return ;

}