Split and Merge functions

void split(InputArray m, OutputArrayOfArrays mv)

Divides a multi-channel array into several single-channel arrays.

Parameters:

• src – input multi-channel array.
• mv – output array or vector of arrays; in the first variant of the function the number of arrays must match src.channels(); the arrays themselves are reallocated, if needed.

void merge(InputArrayOfArrays mv, OutputArray dst)

Creates one multichannel array out of several single-channel ones.

Parameters:

• mv – input array or vector of matrices to be merged; all the matrices in mv must have the same size and the same depth.
• dst – output array of the same size and the same depth as mv[0]; The number of channels will be the total number of channels in the matrix array.

Example:

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#include "opencv2/objdetect/objdetect.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>

using namespace std;
using namespace cv;

int main()
{
    Mat src=imread("image.jpg",1);    
    namedWindow("src",1);imshow("src",src);

    // Split the image into different channels
    vector<Mat> rgbChannels(3);
    split(src, rgbChannels);

    // Show individual channels
    Mat g, fin_img;
    g = Mat::zeros(Size(src.cols, src.rows), CV_8UC1);
    
    // Showing Red Channel
    // G and B channels are kept as zero matrix for visual perception
    {
    vector<Mat> channels;
    channels.push_back(g);
    channels.push_back(g);
    channels.push_back(rgbChannels[2]);

    /// Merge the three channels
    merge(channels, fin_img);
    namedWindow("R",1);imshow("R", fin_img);
    }

    // Showing Green Channel
    {
    vector<Mat> channels;
    channels.push_back(g);
    channels.push_back(rgbChannels[1]);
    channels.push_back(g);    
    merge(channels, fin_img);
    namedWindow("G",1);imshow("G", fin_img);
    }

    // Showing Blue Channel
    {
    vector<Mat> channels;
    channels.push_back(rgbChannels[0]);
    channels.push_back(g);
    channels.push_back(g);
    merge(channels, fin_img);
    namedWindow("B",1);imshow("B", fin_img);
    }

    waitKey(0);
    return 0;
}

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