OpenCV處理透明圖片，主要是考慮圖片的疊加。

//主函式操作
Mat dest,srcAlpha;

//-1表示讀取帶有alpha通道的圖片
srcAlpha = imread("1.png",-1);
dest= imread("2.png");

//(0,0)設定對srcAlpha的疊加
mapToMat(srcAlpha, dest, 0, 0);

void mapToMat(const cv::Mat &srcAlpha, cv::Mat &dest, int x, int y)
{
    int nc = 3;
    int alpha = 0;

    for (int
 
 j = 0; j < srcAlpha.rows; j++)
    {
        for (int i = 0; i < srcAlpha.cols*3; i += 3)
        {
            // 目的圖片為三通道，所以是三通道的遍歷、四通道的源圖
            // i/3*4表示第i/3個畫素的位置 
            // i/3*4 + 3表示本畫素的alpha通道的值
            alpha = srcAlpha.ptr<uchar>(j)[i / 3*4 + 3];
            //alpha = 255-alpha;
            if
 
(alpha != 0) //4通道影象的alpha判斷
            {
                for (int k = 0; k < 3; k++)
                {
                    // if (src1.ptr<uchar>(j)[i / nc*nc + k] != 0)
                    if( (j+y < dest.rows) && (j+y>=0) &&
                        ((i+x*3) / 3*3 + k < dest.cols*3
 
) && ((i+x*3) / 3*3 + k >= 0) &&
                        (i/nc*4 + k < srcAlpha.cols*4) && (i/nc*4 + k >=0) )
                    {
                        dest.ptr<uchar>(j+y)[(i+x*nc) / nc*nc + k] = srcAlpha.ptr<uchar>(j)[(i) / nc*4 + k];
                    }
                }
            }
        }
    }
}

合併兩張圖片

///////////////////////////////////
			Mat img_left = imread("02.jpg");
			Mat img_right = imread("testface.png");

			Size size(img_left.cols + img_right.cols, MAX(img_left.rows, img_right.rows));

			Mat img_merge;
			Mat outImg_left, outImg_right;

			img_merge.create(size, CV_8UC3);
			img_merge = Scalar::all(0);
			outImg_left = img_merge(Rect(0, 0, img_left.cols, img_left.rows));
			outImg_right = img_merge(Rect(img_left.cols, 0, img_right.cols, img_right.rows));


			img_left.copyTo(outImg_left);
			img_right.copyTo(outImg_right);
			imshow("merge", img_merge);

Taily老段的微信公眾號，歡迎交流學習