OPENCV多通道分离与合成、图像格式转换

1. C++: void split(const Mat& src, Mat*mvbegin);
2. C++: void split(InputArray m,OutputArrayOfArrays mv);

合成

1. C++: void merge(const Mat* mv, size_tcount, OutputArray dst)
2. C++: void merge(InputArrayOfArrays mv,OutputArray dst)

例子：

Mat srcImage;
Mat imageROI;
vector channels;
srcImage = cv::imread("test.jpg");

// 把一个3通道图像转换成3个单通道图像
split(srcImage,channels);//分离色彩通道

imageROI=channels.at(0);
addWeighted(imageROI(Rect(385,250,logoImage.cols,logoImage.rows)),1.0,
logoImage,0.5,0.,imageROI(Rect(385,250,logoImage.cols,logoImage.rows)));
merge(channels,srcImage4);

namedWindow("sample");
imshow("sample",srcImage);

图像格式的转换

char ar1[4]={10,20,30,40};//注意不能用Int类型来初始化

Mat src=Mat(2,2,CV_8U,ar1);

Mat dst;

src.convertTo(dst,CV_32F);//转换成32F的矩阵。值不变

src.convertTo(dst,CV_32F,1/255);//转换成32F的矩阵。值区域改为0~255

src.convertTo(dst, 
CV_8UC3, -1.0, 255.0); // inverse the mask matrix means I_new(x,j) = -1*I(x,j) + 255.