OpenCV, Dlib - Mat object outputed as black image

Question

I have 4 channel Mat object. I'm trying(as part of a process), to convert it to dlib data(make some changes), and back to Mat .

For some reason, the final output is complete black. I'm trying to be as much efficient in terms of runtime.

cv::Mat image;
cv::cvtColor(image, image, CV_RGBA2BGR); //convert to 3 channels
//COPY pointer saves runtime
dlib::array2d<dlib::rgb_pixel> dlibimg;
dlib::assign_image(dlibimg, dlib::cv_image<dlib::bgr_pixel>(cvimg));
image = dlib::toMat(dlibimg); //black

Any suggestions, why the output is complete black?

Answer 1

dlib::array2d<dlib::rgb_pixel> dlibimg should be

`dlib::array2d<dlib::rgb_alpha_pixel> dlibimg`  

as you have given 4 channel Mat image.