Can we create n channel image in opencv,n will be around 20

Question

Presently Iam working in finding disparity of stereo pair. I have got a situation in creating 20 channel data set, When I declare array of 3 dimension it was giving error, Instead can I create image of 20 channels so that I can store data. If I can what are the additional conditions I have to include to get results without any error of memory allocation or sort of .... Creating an Image of 20 channels will be even comfortable for me...

Answer 1

The C++ interface of OpenCV presents cv::Mat, which replaces and improves the IplImage type of the C interface. This new type provides several constructors, including the one below which can be used to specify the desired number of channels through the param type:

Mat::Mat(int rows, int cols, int type)

Sample code:

#include <cv.h>
#include <highgui.h>
#include <iostream>

void test_mat(cv::Mat mat)
{
    std::cout << "Channels: " << mat.channels() << std::endl;
}

int main(int argc, char* argv[])
{
    cv::Mat mat20(1024, 768, CV_8UC(20));
    test_mat(mat20);

    return 0;
}

Answer 2

Opencv implements template class for small matrices whose type and size are known at compilation time:

template<typename _Tp, int m, int n> class Matx {...};

You can create a specified template of a partial case of Matx, which is cv::Vec like those already written in opencv for 1,2, or 3 "channels" like that:

typedef Vec<uchar, 3> Vec3b; // 3 channel -- written in opencv 
typedef Vec<uchar, 20> Vec20b; // the one you need

And then, declare a Matrix of your new (20 channel of uchar) object:

cv::Mat_<Vec20b> myMat;
myMat.at<Vec20b>(i,j)(10) = .. // access to the 10 channel of pixel (i,j)