从 batch 中提取矩阵，表示为 Tensor

Question

我在 C++ 中使用 Tensorflow。我正在使用经过训练的模型从输入图像中提取补丁。

我的输出张量（在会话运行之后）是 outputs 并且在 outputs[0] 中有一批 N 个补丁，MxMxD。

auto patches = outputs[0].tensor<float, 4>();

现在，我想使用 OpenCV 显示此图像，特别是，我想使用 cv::eigen2cv 函数，给定一个 Eigen::Matrix 给我一个 cv::Mat。

问题是我需要遍历这个输出张量并为每个元素提取一个 Eigen::Matrix.

我已经在此处尝试了建议的解决方案：但由于 Eigen 错误，我什至无法编译代码：EIGEN_STATIC_ASSERT_VECTOR_ONLY:

const auto patch_side = 256;
int batch_id = 0;
using Matrix =
    Eigen::Matrix<float, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor>;
for (auto i = 0; i < grid_shape.second; ++i) {
    for (auto j = 0; j < grid_shape.first; ++j) {
        auto size = patch_side * patch_side * depth;
        auto map =
            Eigen::Map<Matrix>(patches.data() + batch_id * size, size);
        // Eigen::Matrix4f m = map;
        Matrix m = map;

        cv::Mat p;
        cv::eigen2cv(m, p);
        cv::imshow("p", p);
        cv::waitKey();
        /*
        ml(cv::Rect(i * patch_side, j * patch_side, patch_side,
                    patch_side)) =
            cv::Mat(cv::Size(patch_side, patch_side), CV_32F, patches.slice
                    patches.data() + (i + j) * patch_side * patch_side);
                    */

        std::cout << "i,j" << i << "," << j << "\n";
        batch_id++;
    }
}

那么，我怎样才能从 Eigen::Tensor（或 tf::Tensor）中得到一个可以用于 cv::eigen2cv 的矩阵？

Answer 1

环顾四周 the documenation of OpenCV，考虑到 TensorFlow 张量始终是行优先的，您应该能够像这样做：

const auto patch_side = 256;
int batch_id = 0;
for (auto i = 0; i < grid_shape.second; ++i) {
    for (auto j = 0; j < grid_shape.first; ++j) {
        auto size = patch_side * patch_side * depth;
        cv::Mat p(patch_side, patch_side, CV_32FC(depth), patches.data() + batch_id * size);
        cv::imshow("p", p);
        cv::waitKey();
        /*
        ml(cv::Rect(i * patch_side, j * patch_side, patch_side,
                    patch_side)) =
            cv::Mat(cv::Size(patch_side, patch_side), CV_32F, patches.slice
                    patches.data() + (i + j) * patch_side * patch_side);
                    */

        std::cout << "i,j" << i << "," << j << "\n";
        batch_id++;
    }
}

请注意，这不是复制张量数据，而是创建指向它的 cv::Mat。

从 batch 中提取矩阵，表示为 Tensor

Extract matrix from batch, represented as Tensor

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eigen

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