//dlib::array2d is an image already, you can use it for any dlib's image functions  
    //load image:  
    dlib::array2d<dlib::rgb_pixel> img_rgb;//使用dlib載入彩色的RGB影象  
    dlib::load_image(img_rgb, "test_image.jpg");  


    //convert to greyscale:  
    dlib::array2d<unsigned char> img_gray;//使用dlib載入灰度影象  
 

    dlib::load_image(img_gray, "test_image.jpg");  
    //或者  
    dlib::assign_image(img_gray, img_rgb);  


    //converto to OpenCV Image (cv::Mat):  
    #include <dlib/opencv.h>  
    #include <opencv2/opencv.hpp>  
    cv::Mat img = dlib::toMat(img_rgb);//RGB影象  
    cv::Mat img = dlib::toMat
 
(img_gray);//灰度影象  


    //get image from OpenCV:  
    #include <dlib/opencv.h>  
    #include <opencv2/opencv.hpp>  
    cv::Mat img = cv::imread("test_image.jpg")  
    dlib::cv_image<rgb_pixel> dlib_img(img); // only stores pointer, no deep copy  
    //Documentation is here. There are a lot of well-documented examples, you should start from them. Special example about array2ddlib array2d轉 OpenCV Mat時顏色失真