openCV3.4 cvSaveImage 报错error: (-215:Assertion failed) (flags & FIXED_TYPE) != 0 in function 'type'

Question

在opencv3.4中，使用C语言对图像进行存储

    IplImage* srcshow = cvLoadImage("1.png", 1);
    if(srcshow == NULL){
        printf("NULL\n");
        return 0;
    }
    printf("while\n");
    CvMat *matshow = cvCreateMat(srcshow->height, srcshow->width, CV_64FC3);    //注意height和width的顺序
    cvConvert(srcshow, matshow);    //深拷贝
        cvSaveImage("2.png", matshow, 0);

报错
terminate called after throwing an instance of 'cv::Exception'
what(): OpenCV(3.4.3)/modules/core/src/matrix_wrap.cpp:800: error: (-215:Assertion failed) (flags & FIXED_TYPE) != 0 in function 'type'

之前尝试过保存IplImage和cvMat均是这个错误信息
获悉将转换为Mat后可以正常存储，
但因一些外部原因，只能使用C，无法使用C++，
求解惑，谢谢！

Answer 1

https://blog.csdn.net/oMoDao1/article/details/80833385