OpenCV/ImageProcessing/ExtractChannel

You will want to make sure that you include the imgproc, highgui, and core, libraries in your project settings.

ExtractChannel.cpp

#include "highgui.h" // required for imread()
#include "cv.h"
 
#include <iostream>
#include <vector>
 
int main(int, char*argv[])
{
  cv::Mat image = cv::imread(argv[1], CV_LOAD_IMAGE_COLOR);
 
  if(image.empty())
  {
    std::cout << "Can't read the image" << std::endl;
    return -1;
  }
  std::vector<cv::Mat> channels;
  cv::split(image, channels);
  cv::Mat r_channel = channels[0];
 
  for(int i=0; i < r_channel.rows; i++)
  {
    for(int j=0; j < r_channel.cols; j++)
    {
      std::cout << r_channel.at<uchar>(i,j) << std::endl;
    }
  }
 
  return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.6)
 
PROJECT(ExtractChannel)
 
FIND_PACKAGE(OpenCV REQUIRED )
INCLUDE_DIRECTORIES( ${OPENCV_INCLUDE_DIR} )
 
ADD_EXECUTABLE(ExtractChannel ExtractChannel.cpp)
TARGET_LINK_LIBRARIES(ExtractChannel ${OpenCV_LIBS})