如何使用C++在OpenCV中从多通道图像中读取像素值？

我们声明了三个变量，分别是'blue_Channel'、'green_channel'和'red_channel'。这些变量的目的是保存像素值。我们在'for循环'中使用了这些变量。然后，我们声明了一个名为'color_Image_Matrix'的矩阵。

这个方法的语法如下：

blue_Channel = color_image_Matrix.at<Vec3b>(i, j)[0];

我们使用了一张BGR图像。它有三个通道。这些通道维护特定的顺序，color_image_Matrix.at<Vec3b> (i, j) 表示位于(i, j)位置的像素值，[0]表示第一个通道。例如，如果我们将这行代码写成如下形式：

blue_Channel=color_image_Matrix.at<Vec3b> (30, 35) [0];

It means the variable 'blue_Channel' will have the first channel's pixel value located at(30, 35). This is how we can access the pixel values using OpenCV.

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The following program reads pixel values of different RGB images and displays the different channel pixel's value in a console window.

Example

#include<iostream>
#include<opencv2/highgui/highgui.hpp>
using namespace std;
using namespace cv;
int main() {
   int blue_Channel;
   int green_Channel;
   int red_Channel;
   Mat color_image_Matrix; //Declaring a matrix to load the image//
   color_image_Matrix = imread("colors.jpg"); //loading image in the matrix//
   //Beginning of for loop to read pixel values of blue channel//
   for (int i = 0; i < color_image_Matrix.rows; i++)//loop for rows// {
      for (int j = 0; j < color_image_Matrix.cols; j++) {
         //loop for columns//
         blue_Channel = color_image_Matrix.at<Vec3b>(i, j)[0];
         //To read the value of first channel.Here the blue channel is first channel//
         cout << "Value of pixel of blue channel" << "(" << i << "," << j << ")" << "="
            << blue_Channel << endl; //showing the values in console window//
      }
   }
   //End of for loop to read pixel values of blue channel//
   //Beginning of for loop to read pixel values of green channel//
   for (int i = 0; i < color_image_Matrix.rows; i++)//loop for rows// {
      for (int j = 0; j < color_image_Matrix.cols; j++)//loop for columns// {
         green_Channel = color_image_Matrix.at<Vec3b>(i, j)[1];
         //To read the value of first channel.Here the green channel is first channel//
         cout << "Value of pixel of green channel" << "(" << i << ","
            << j << ")" << "=" << blue_Channel << endl;//showing the values in console window//
      }
   }
   //End of for loop to read pixel values of green channel//
   //Beginning of for loop to read pixel values of red channel//
   for (int i = 0; i < color_image_Matrix.rows; i++)//loop for rows// {
      for (int j = 0; j < color_image_Matrix.cols; j++)//loop for columns// {
         red_Channel = color_image_Matrix.at<Vec3b>(i, j)[2];
         //To read the value of first channel.Here the red channel is first channel//
         cout << "Value of pixel of red channel" << "(" << i << "," <<
            j << ")" << "=" << blue_Channel << endl; //showing the values in console window//
      }
   }
   //End of for loop to read pixel values of red channel//
   if (waitKey(0)==27);
      cout << "Image read successfully&hellip;!";
      return 0;
}

输出

Image read successfully...

这个程序运行需要几分钟时间。它从不同的通道读取每个像素值。这就是为什么显示完整结果需要几分钟的原因。