opencv cvSplit cvMerge

/* Splits a multi-channel array into the set of single-channel arrays or
extracts particular [color] plane */
CVAPI(void)  cvSplit( const CvArr* src, CvArr* dst0, CvArr* dst1,
CvArr* dst2, CvArr* dst3 );

作用：将多通道图像分离为单通道图像

src：多通道源图像

dst0、dst1、dst2、dst3：单通道结果图像

源图像和结果图像的大小相同，深度类型相同，仅有通道类型不同

##############################################################

/* Merges a set of single-channel arrays into the single multi-channel array
or inserts one particular [color] plane to the array */
CVAPI(void)  cvMerge( const CvArr* src0, const CvArr* src1,
const CvArr* src2, const CvArr* src3,
CvArr* dst );

作用：将单通道图像合并为多通道图像

src0、src1、src2、src3：单通道源图像

dst：多通道结果图像

源图像和结果图像的大小相同，深度类型相同，仅有通道类型不同

###########################################################

程序：将图像lena.jpg分离为三个单通道图像c1、c2、c3，再将其合并为单通道图像（蓝、绿、红）

void splitAndMerge(void)
{
IplImage *img=cvLoadImage("lena.jpg");
IplImage *c1=cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *c2=cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *c3=cvCreateImage(cvGetSize(img), img->depth, 1);
IplImage *rImg=cvCreateImage(cvGetSize(img), img->depth, 3);
IplImage *gImg=cvCreateImage(cvGetSize(img), img->depth, 3);
IplImage *bImg=cvCreateImage(cvGetSize(img), img->depth, 3);

if (NULL == img || NULL == c1 || NULL == c2 || NULL == c3 || NULL == rImg || NULL == gImg || NULL == bImg)
exit(0);

cvSplit(img, c1, c2, c3, NULL);

cvNamedWindow("img");
cvShowImage("img", img);

cvZero(rImg);
cvZero(gImg);
cvZero(bImg);
cvMerge(c1, NULL, NULL, NULL, bImg);
cvMerge(NULL, c2, NULL, NULL, gImg);
cvMerge(NULL, NULL, c3, NULL, rImg);

cvNamedWindow("rImg");
cvNamedWindow("gImg");
cvNamedWindow("bImg");
cvShowImage("rImg", rImg);
cvShowImage("gImg", gImg);
cvShowImage("bImg", bImg);
cvWaitKey(0);

cvReleaseImage(&img);
cvReleaseImage(&c1);
cvReleaseImage(&c2);
cvReleaseImage(&c3);

cvReleaseImage(&rImg);
cvReleaseImage(&gImg);
cvReleaseImage(&bImg);

cvDestroyAllWindows();
}