【OpenCV：從零到一】05：圖像混合和疊加

前言
這是我《OpenCV：從零到一》專欄的第五篇博客，想看跟多請戳這。
本文概要
multiply
addWeighted
Rect以及常用的矩形類
copyTo的另一種用法
案例代碼
大概內容：圖片線性混合、乘積混合、疊加。

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

using std::cout;
using std::endl;
using namespace cv;

int main(int argc, char** argv) {
	Mat linux, windows, dst1, dst2;
	linux = imread("D:\\86186\\Documents\\opencv\\linux.jpg");
	windows = imread("D:\\86186\\Documents\\opencv\\windows.jpg");
	
	if (!linux.data) {
		cout << "could not load image Linux Logo..." << endl;
		return -1;
	}
	if (!windows.data) {
		cout << "could not load image WIN7 Logo..." << endl;
		return -1;
	}
	if (linux.rows == windows.rows && linux.cols == windows.cols && linux.type() == windows.type()) {
		//混合圖像(無論是乘還是加)的大小和類型都要一樣

		double alpha = 0.5;//設置混合權重
		addWeighted(linux, alpha, windows, (1.0 - alpha), 0.0, dst1);
		imshow("addWeightedDst", dst1);
		imshow("linux", linux);
		imshow("windows", windows);

		multiply(linux, windows, dst2, 1.0);//Calculates the per-element scaled product of two arrays.
		imshow("multiplyDst", dst2);
		
		Mat smallLinux = imread("D:\\86186\\Documents\\opencv\\smallLinux.jpg");
		Mat imageROI = windows(Rect(20, 20, smallLinux.cols, smallLinux.rows));//ROI region of image
		Mat mask= imread("D:\\86186\\Documents\\opencv\\smallLinux.jpg", IMREAD_GRAYSCALE);//IMREAD_GRAYSCALE==0,mask必須是灰度圖像
		smallLinux.copyTo(imageROI, mask);//copyTo的另一種用法是用來疊加圖片
		imshow("smallLinux", windows);
	}
	else {
		printf("could not blend images , the size of images is not same...\n");
		return -1;
	}
	waitKey(0);
	return 0;
}

運行效果:

解析及注意事項

• 混合的圖像要大小一樣，疊加的圖像要比原圖像小，並且位置要不超出原圖像
• 線性混合公式：
  
• ROI區域創建好之後可以利用copyTo將和ROI一樣大小的圖片疊加到ROI所在的區域上面

全註釋代碼

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

using std::cout;
using std::endl;
using namespace cv;

int main(int argc, char** argv) {
	Mat linux, windows, dst1, dst2;
	linux = imread("D:\\86186\\Documents\\opencv\\linux.jpg");
	windows = imread("D:\\86186\\Documents\\opencv\\windows.jpg");

	if (!linux.data) {
		cout << "could not load image Linux Logo..." << endl;
		return -1;
	}
	if (!windows.data) {
		cout << "could not load image WIN7 Logo..." << endl;
		return -1;
	}

	if (linux.rows == windows.rows && linux.cols == windows.cols && linux.type() == windows.type()) {
		//混合圖像的大小和類型都要一樣(無論是乘還是加)
		double alpha = 0.5;//設置混合權重
		addWeighted(linux, alpha, windows, (1.0 - alpha), 0.0, dst1);
		/*
		InputArray src1,//first input array.
		double alpha,//weight of the first array elements.
		InputArray src2,//second input array of the same size and channel number as src1.大小和通道要和圖一相同
		double beta,//weight of the second array elements.
		double gamma,//scalar added to each sum.
		OutputArray dst,//scalar added to each sum.
		int dtype = -1 	//optional depth of the output array;
		*/
		imshow("addWeightedDst", dst1);
		imshow("linux", linux);
		imshow("windows", windows);

		multiply(linux, windows, dst2, 1.0);//Calculates the per-element scaled product of two arrays.
		/*
		計算兩個數組的每個元素縮放後的乘積。
		參數:
		InputArray src1,
		InputArray src2,//second input array of the same size and the same type as src1
		OutputArray dst,
		double scale = 1,
		int dtype = -1
		dst(I)=saturate(scale * src1(I) * src2(I))
		*/
		imshow("multiplyDst", dst2);

		Mat smallLinux = imread("D:\\86186\\Documents\\opencv\\smallLinux.jpg");
		Mat imageROI = windows(Rect(20, 20, smallLinux.cols, smallLinux.rows));//ROI region of image
		Mat mask = imread("D:\\86186\\Documents\\opencv\\smallLinux.jpg", IMREAD_GRAYSCALE);//IMREAD_GRAYSCALE==0,mask必須是灰度圖像
		smallLinux.copyTo(imageROI, mask);//copyTo的另一種用法是用來疊加圖片
		imshow("smallLinux", windows);
		/*
		rect是一個矩形類,參數有四個(當然還有其他重載),建議前兩個參數設置小一些,並且區域要小於原圖,否則會越界
		_Tp x,//x coordinate of the top-left corner 矩形左上角的x座標
		_Tp y,//y coordinate of the top-left corner 矩形左上角的y座標
		_Tp height,//height of the rectangle 矩形高度
		_Tp width,//width of the rectangle  矩形寬度
		宏定義關係如下
		typedef Rect_<int> cv::Rect2i
		typedef Rect_<float> cv::Rect2f
		typedef Rect_<double> cv::Rect2d

		typedef Rect2i cv::Rect
		*/
	}
	else {
		printf("could not blend images , the size of images is not same...\n");
		return -1;
	}
	waitKey(0);
	return 0;
}

翻譯筆記
ROI region of interest 感興趣區域
coordinate v. 調節，配合；使動作協調；（衣服、傢俱等）搭配；與……形成共價鍵
adj. 同等的，並列的；配位的；座標的
n. 座標；配套服裝；同等的人或物