OpenCV实现彩色图像轮廓 换背景颜色

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有时候我们需要不一样颜色的证件照，下面就用OpenCV来实现证件照的蓝底、红底等换颜色；

代码如下：

 #include <opencv2/opencv.hpp>
 using namespace cv;
 int main()
 {
     Mat g_srcImage = imread("11.jpg");
     imshow("g_srcImage", g_srcImage);
     waitKey();

     vector<Mat> g_vChannels;
     split(g_srcImage, g_vChannels);

     Mat imageBlueChannel = g_vChannels.at();
     Mat imageGreenChannel = g_vChannels.at();
     Mat imageRedChannel = g_vChannels.at();

     Mat img_B = ( * imageBlueChannel - imageGreenChannel - imageRedChannel);
     imshow("img_B", img_B);
     waitKey();

     threshold(img_B, img_B, , , CV_THRESH_OTSU);
     imshow("img_B_g", img_B);
     waitKey();

     //对每个轮廓进行分析
     vector <Mat> contours;
     vector <Vec4i> hierarchy;
     double min_area = ;//小于50的认为不是数字

     findContours(img_B, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);

     // fill external contours
     if (!contours.empty() && !hierarchy.empty())
     {
         for (int idx = ; idx < contours.size(); idx++)
         {
             //Mat temp_img(Size(img_B.size()), CV_8U, Scalar(0));
             drawContours(img_B, contours, idx, Scalar(), CV_FILLED, );//填充 形成区域

             drawContours(g_srcImage, contours, idx, Scalar(,,), CV_FILLED, );//填充 形成区域

         }
     }
     imshow("g_srcImage11", g_srcImage);
     waitKey();
     imwrite("g_srcImage.bmp", g_srcImage);

 }

效果图：