cvZero()；是让矩阵的值都为0，有初始化的作用，或者说清零~
比如说：IplImage img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);%创建一幅图像
cvZero(img);%相当于初始化图片，值都为0，矩阵大小为640*480
cvShowImage("img",img);%就显示一幅黑色，且值都为零的图像
cvCircle(CvArr* img, CvPoint center, int radius, CvScalar color, int thickness=1, int lineType=8, int shift=0)
img为图像指针，单通道多通道都行，不需要特殊要求
center为画圆的圆心坐标
radius为圆的半径
color为设定圆的颜色，比如用CV_RGB(255, 0,0)设置为红色
thickness为设置圆线条的粗细，值越大则线条越粗，为负数则是填充效果
1: #include"stdafx.h"
2: #include"opencv2/opencv.hpp"
3: #include"opencv2/opencv_modules.hpp"
4: #include"cv.h"
5: #include"cxcore.h"
6: #include"highgui.h"
7:
8: #define RaderImageWdith 720
9: #define RaderImageHeight 720
10:
11:
12: /*******************从文件中读取一副图像并在屏幕中显示***********************/
13: int main()
14: {
15: /*********************雷达数据处理*********************/
16: IplImage* RaderImage = cvCreateImage(cvSize(RaderImageWdith,RaderImageHeight),IPL_DEPTH_8U,1);
17: cvZero(RaderImage);
18: int dx = RaderImageWdith/2;
19: int dy = RaderImageHeight*3/4;
20: cvCircle(RaderImage, cvPoint(dx,dy),3, CV_RGB(0,255,255), -1, 8,0);
21: cvShowImage("RaderImage",RaderImage);
22:
23:
24:
25:
26:
27:
28:
29:
30: //定义一个字符指针，并指向图片所在的位置
31: char *PFileName;
32: PFileName = "D:\Pictures\parrot.jpg";
33: //读取一张图片并载入内存，并用一个数据结构指针指向这张图片
34: IplImage *Img = cvLoadImage(PFileName);
35: if(NULL == Img)//如果读入失败，退出程序
36: exit(1);
37: //创建一个窗体，标题为Example，自增益
38: cvNamedWindow("Example",1);
39:
40: //用指针指向图像的数据区头部
41: uchar *pchar;
42: int width = Img ->width; //读取图像宽度
43: int height = Img ->height; //读取图像高度
44: int channel = Img ->nChannels; //读取图像的通道数
45: int widthStep = Img ->widthStep;//读取图像一行像素所占的字节数
46: int i,j;
47: for(i = 0; i < height ; i++) //以下是遍历一副图像中的每个像素点
48: {
49: pchar = (uchar*)Img ->imageData + i * widthStep;
50: for(j = 0; j < width; j++)
51: {
52: uchar *temp = pchar + j * channel;
53: temp[0] += 10; //通道B
54: temp[1] += 10; //通道G
55: temp[2] += 10; //通道R
56: }
57: }
58: //在窗口中显示这张图片
59: cvShowImage("Example",Img);
60: //暂停程序，等待用户触发一个按键
61: cvWaitKey(0);
62: //释放图像所分配的内存空间
63: cvReleaseImage(&Img);
64: //销毁窗口
65: cvDestroyWindow("Example");
66: return 0;
67: }