如何循环遍历 Matrix 数据的显示方式？

Question

情况

我有一个 300 列和 1 行的矩阵。当我 cout << 它时，我得到：

[  0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0]

...形式为 I expect/want.

问题

但是，当我循环遍历它时，我想在每次迭代中获取每个单个值。但是，我得到的顺序略有不同（尽管有时它非常相似）。

代码

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/imgcodecs/imgcodecs.hpp"

using namespace std;
using namespace cv;

int main(){


  Mat test(1,300,CV_8UC1, 255);
    cout << test;

    Mat frame, grayFrame,threshFrame,smaller;

    VideoCapture cap(0);

    while(true){
        cap.read(frame);
        cvtColor(frame, grayFrame, cv::COLOR_RGB2GRAY);
        threshold(grayFrame, threshFrame, 160, 255, THRESH_BINARY);
        smaller = threshFrame(Rect(0,0,300,1));
        cout << smaller;

        for(int x=0;x<smaller.cols;x++){
            int color = smaller.at<Vec3b>(x,1)[0];
            cout << color;

        }

        break;        
    }

}

...奇怪的输出不遵循与原始矩阵完全相同的 0 和 255 顺序：

00000000000000000000000000000000000000000000000000000000000000000000000000000000000002552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552552550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

矩阵一开始有很多 0，很少有 255，而循环输出有很多 255，而不是很多开始的 0。

本质上，我想遍历首先显示的矩阵，并在每次迭代中获取每个值。所以 0,0,255,255...等等

Answer 1

你在看垃圾。

at 函数需要 (row, col)，而不是 (x, y)。请记住 row = y 和 col = x.
如果你的矩阵只有一行，行索引必须是0，而不是1。
你的矩阵是unsigned char的单通道，所以你需要使用at<uchar>

在实践中，使用：

uchar color = smaller.at<uchar>(0, x);
cout << int(color);

或使用索引：

uchar color = smaller.at<uchar>(x);

如何循环遍历 Matrix 数据的显示方式？

How do I loop through Matrix data how it appears?

c++

opencv

computer-vision