《学习OpenCV》第三章练习（参考代码）第7题

#include<stdio.h>
#include<cv.h>
#include<highgui.h>

int main(int argc, char** argv){
	IplImage* img = cvLoadImage("E:\\1.jpg");
	IplImage* red = cvCreateImage(cvGetSize(img), img->depth, 1);
	IplImage* green = cvCreateImage(cvGetSize(img), img->depth, 1);
	IplImage* blue = cvCreateImage(cvGetSize(img), img->depth, 1);
	IplImage* green_image = cvCreateImage(cvGetSize(img), img->depth, img->nChannels);
	cvSplit(img, red, green, blue, NULL);
	cvZero(red);
	cvZero(blue);
	cvMerge(red, green, blue, NULL, green_image); 
	cvNamedWindow("GreenChannel", CV_WINDOW_AUTOSIZE);
	cvShowImage("GreenChannel", green_image);

	//克隆这个绿图两次（分别命名为clone1和clone2）
	//
	IplImage* clone1 = cvCloneImage(green);
	IplImage* clone2 = cvCloneImage(green);

	//求出这个绿色平面的最大值和最小值
	//
	double min;
	double max;
	CvPoint minPtr;
    CvPoint maxPtr;
	cvMinMaxLoc(green, &min, &max, &minPtr, &maxPtr); //注意：输入的图象必须是单通道的
	printf("Minimum: %lf, Position: (%d, %d) \n", min, minPtr.x, minPtr.y);
	printf("Maximum: %lf, Position: (%d, %d) \n", max, maxPtr.x, maxPtr.y);

	//将clone1的所有元素赋值为thresh = (unsigned char)((最大值-最小值)/2.0)
	//
	double thresh = (max-min)/2;
	cvZero(clone1);
	cvAddS(clone1, cvScalar(thresh), clone1);
	
	//将clone2所有元素赋值为0，然后调用函数cvCmp(green_image, clone1, clone2, CV_CMP_GE)。
	//现在clone2将是一个标识绿图中值超过thresh的掩码图象。
	//

	//如果green中的元素大于或等于clone1中对应位置的元素，那么clone2对应位置的像素值被设为255
	cvCmp(green, clone1, clone2, CV_CMP_GE);

	//最后，使用cvSubS(green_image, thresh/2, green_image, clone2)函数并显示结果
	//
	cvSubS(green, cvScalar(thresh/2), green, clone2);

	IplImage* resultImg = cvCreateImage(cvGetSize(img), img->depth, img->nChannels);
	cvMerge(red, green, blue, NULL, resultImg);

	cvNamedWindow("FinalResult", CV_WINDOW_AUTOSIZE);
	cvShowImage("FinalResult", resultImg);

	cvWaitKey(0);
	cvReleaseImage(&img);
	cvReleaseImage(&red); 
	cvReleaseImage(&green);
	cvReleaseImage(&blue);
	cvReleaseImage(&green_image);
	cvReleaseImage(&clone1);
	cvReleaseImage(&clone2);
	cvDestroyWindow("GreenChannel");
}