Question

场合

我有一个300列和1行的矩阵。当我cout <<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]

...这是我期望/想要的形式。

问题

然而，当我遍历它时，我希望每次迭代都获得每个单值。但是，相反，我的顺序略有不同（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

矩阵最初有很多0，很少有255，其中循环输出有很多255，而不是从0开始。

基本上，我想循环显示首先显示的矩阵，并且对于每次迭代，获取每个值。所以0,0,255,255 ......等等。

Answer 1

你在读垃圾。

at功能需要(row, col)，而不是(x, y)。请记住row = y和col = x。
如果您的矩阵只是一行，则行索引必须为0，而不是1。
您的矩阵是单个无符号字符的通道，因此您需要使用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);

如何循环显示Matrix数据的显示方式？

1 个答案: