在 OpenCV 中将 Mat 转换为数组/矢量 [英] Convert Mat to Array/Vector in OpenCV

问题描述

我是 OpenCV 的新手.最近，我在寻找 OpenCV 函数以将 Mat 转换为 Array 时遇到了麻烦.我研究了 OpenCV API 中可用的 .ptr 和 .at 方法，但我无法获得正确的数据.我想要从 Mat 到 Array 的直接转换(如果可用，如果不是 Vector).我需要 OpenCV 函数，因为代码必须在 Vivado HLS 中进行高级综合.请帮忙.

I am novice in OpenCV. Recently, I have troubles finding OpenCV functions to convert from Mat to Array. I researched with .ptr and .at methods available in OpenCV APIs, but I could not get proper data. I would like to have direct conversion from Mat to Array(if available, if not to Vector). I need OpenCV functions because the code has to be undergo high level synthesis in Vivado HLS. Please help.

推荐答案

如果Mat mat的内存是连续的(它的所有数据都是连续的)，可以直接把它的数据变成一维数组:

If the memory of the Mat mat is continuous (all its data is continuous), you can directly get its data to a 1D array:

std::vector<uchar> array(mat.rows*mat.cols*mat.channels());
if (mat.isContinuous())
    array = mat.data;

否则，您必须逐行获取其数据，例如到二维数组:

Otherwise, you have to get its data row by row, e.g. to a 2D array:

uchar **array = new uchar*[mat.rows];
for (int i=0; i<mat.rows; ++i)
    array[i] = new uchar[mat.cols*mat.channels()];

for (int i=0; i<mat.rows; ++i)
    array[i] = mat.ptr<uchar>(i);

<小时>

更新:如果您使用 std::vector 会更容易，您可以这样做:

---

UPDATE: It will be easier if you're using std::vector, where you can do like this:

std::vector<uchar> array;
if (mat.isContinuous()) {
  // array.assign(mat.datastart, mat.dataend); // <- has problems for sub-matrix like mat = big_mat.row(i)
  array.assign(mat.data, mat.data + mat.total()*mat.channels());
} else {
  for (int i = 0; i < mat.rows; ++i) {
    array.insert(array.end(), mat.ptr<uchar>(i), mat.ptr<uchar>(i)+mat.cols*mat.channels());
  }
}

ps:对于其他类型的cv::Mat，比如CV_32F，你应该这样做:

p.s.: For cv::Mats of other types, like CV_32F, you should do like this:

std::vector<float> array;
if (mat.isContinuous()) {
  // array.assign((float*)mat.datastart, (float*)mat.dataend); // <- has problems for sub-matrix like mat = big_mat.row(i)
  array.assign((float*)mat.data, (float*)mat.data + mat.total()*mat.channels());
} else {
  for (int i = 0; i < mat.rows; ++i) {
    array.insert(array.end(), mat.ptr<float>(i), mat.ptr<float>(i)+mat.cols*mat.channels());
  }
}

<小时>

UPDATE2:对于OpenCV Mat数据连续性，可以总结如下:

---

UPDATE2: For OpenCV Mat data continuity, it can be summarized as follows:

• 由 imread()、clone() 或构造函数创建的矩阵将始终是连续的.
• 矩阵不连续的唯一时间是它从现有矩阵(即，借用的数据在大矩阵中是连续的，例如 1. 单行；2. 具有完整原始宽度的多行)借用数据时根据大垫子的投资回报率创建).

• Matrices created by imread(), clone(), or a constructor will always be continuous.
• The only time a matrix will not be continuous is when it borrows data (except the data borrowed is continuous in the big matrix, e.g. 1. single row; 2. multiple rows with full original width) from an existing matrix (i.e. created out of an ROI of a big mat).

请查看此代码片段进行演示.

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