opencv - 访问多维 cv::Mat 数组的元素

Question

我无法弄清楚如何正确访问 3D cv::Mat 数组的元素。以下代码在 Vivado HLS 中运行并失败并出现非描述性错误。这是 Vivado HLS 的问题，还是我没有正确读取值？

cv::Mat img = cv::Mat(cv::Size(100,100),CV_MAKETYPE(CV_8U,5));   // should create a 100x100x5 array

uchar x;
x = img.at<uchar>(0,0,0);    // works fine when reading from third dimension at 0
x = img.at<uchar>(0,0,1);    // fails when reading from third dimension at 1

错误：

@E Simulation failed: SIGSEGV.
ERROR: [SIM 211-100] CSim failed with errors.

Answer 1

Mat::at<T>在使用多维数据时确实存在一些问题。看看：帖子

我建议直接访问像素而不使用Mat::at<T>：

int main(int argc, char** argv)
{

   cv::Mat img = cv::Mat(cv::Size(5, 5), CV_MAKETYPE(CV_8U, 5));  

   std::cout << "Matrix = " << " " << std::endl << img <<std::endl;

   for (unsigned int band = 0; band < img.channels(); band++) {
        for (unsigned int row = 0; row < img.rows; row++) {
             for (unsigned int col = 0; col < img.cols; col++) {


            int  PixelVal = static_cast<int>(img.data[img.channels()*(img.cols*col + row) + band]);
            std::cout << PixelVal << std::endl;

        }
    }
}



return 0;
}

*注意：这是访问 Mat 的一种简单方法，但如果您想提高效率，请使用数据指针。