OpenCV dnn blob issues

C++
1

Hi Community,
I’m working on a project, where I’m trying to convert my image into openCV blob using dnn library of openCV, but I’m getting unusual blob from the function.

#include <opencv2/opencv.hpp>
#include <opencv2/dnn.hpp>

int main(){
    cv::Mat img = cv::imread("/home/vimal/Edge_ai/Vstream/includes/test.jpeg"); 

    if(img.channels() == 3)
        std::cout << "channels are good" << std::endl; 
    
    cv::Mat blob; 
    cv::dnn::blobFromImage(img, blob, 1./255., cv::Size(640, 640), cv::Scalar(), true, false);

    std::cout << blob.channels() << std::endl; 
    std::cout << blob.rows << std::endl; 
    std::cout << blob.cols << std::endl; 

    return 0;

}

but i’m getting the output as,

channels are good

1

-1

-1

kindly help me in this