OPENCV常用小代码

opencv抓取帧：

OpenCV支持从摄像头或视频文件(AVI)中抓取图像并保存为另一视频文件.　一、    从摄像头获取初始化:    CvCapture* capture = cvCaptureFromCAM(0); // capture from video device #0    从视频文件filename.avi获取初始化:    CvCapture* capture = cvCaptureFromAVI("infile.avi");    抓取帧:    IplImage* img = 0;     if(!cvGrabFrame(capture)){               // 抓取一帧,失败退出        printf("Could not grab a frame\n");       exit(0);    }    img=cvRetrieveFrame(capture);            // 恢复获取的帧图像    要从多个摄像头同时获取图像, 首先从每个摄像头抓取一帧. 在抓取动作都结束后再恢复帧图像.      释放抓取源（和释放单幅图像时类似）:    cvReleaseCapture(&capture);      注意由设备抓取的图像是由capture函数自动分配和释放的. 不要试图自己释放它.    获取设备特性:    cvQueryFrame(capture); // this call is necessary to get correct                             // capture properties    int frameH     = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT);    int frameW     = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH);    int fps        = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FPS);    int numFrames  = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_COUNT);    所有帧数似乎只与视频文件有关. 用摄像头时不对，奇怪!!!.      获取帧信息:    float posMsec    =        cvGetCaptureProperty(capture, CV_CAP_PROP_POS_MSEC);    int posFrames    =  (int) cvGetCaptureProperty(capture, CV_CAP_PROP_POS_FRAMES);    float posRatio   =        cvGetCaptureProperty(capture, CV_CAP_PROP_POS_AVI_RATIO);    获取所抓取帧在视频序列中的位置, 从首帧开始按[毫秒]算. 或者从首帧开始从0标号, 获取所抓取帧的标号. 或者取相对位置，首帧为0，末帧为1, 只对视频文件有效.     设定所抓取的第一帧标号:    // 从视频文件相对位置0.9处开始抓取    cvSetCaptureProperty(capture, CV_CAP_PROP_POS_AVI_RATIO, (double)0.9);    只对从视频文件抓取有效. 不过似乎也不成功!!! 

图像差分

void imgDifferUtil::Image_Minus(IplImage *X, IplImage *Y, IplImage *X_Y){    //图像差分函数，将图像1中像素和图像2中对应像素想减，要求X、Y、X_Y大小相同    int i,j,width,height,step,chanel;    unsigned char *dataX, *dataY, *dataX_Y;    width = X->width;    height = X->height;    dataX = (unsigned char *)X->imageData;    dataY = (unsigned char *)Y->imageData;    dataX_Y = (unsigned char *)X_Y->imageData;    step = X->widthStep/sizeof(char);    chanel = X->nChannels;    for(i=0; i<height; i++)        for(j=0; j<width*chanel; j++)            dataX_Y[i*step+j] = abs( dataX[i*step+j] - dataY[i*step+j]);}

opencv变为灰度图及新定义大小

IplImage* toGray(IplImage* img){IplImage* dst = cvCreateImage(cvGetSize(img),img->depth,1);IplImage* tmp =dst ;if(NULL == dst)return NULL;cvCvtColor(img, dst, CV_BGR2GRAY);//cvReleaseImage(&dst);return dst;}IplImage* toNewSize(IplImage* pFrame){    IplImage* dst = cvCreateImage(cv::Size(EVALUATE_IMG_WIDTH,EVALUATE_IMG_HEIGHT),pFrame->depth,pFrame->nChannels); //构造目标图象    if(dst==NULL)    return NULL ;    cvResize(pFrame,dst,CV_INTER_NN);    return dst ;}

显示灰度

void printGrayScale(IplImage *src){int width=src->width;//图片宽度int height = src->height;//图片高度for (size_t row=0;row<height;row++){uchar* ptr = (uchar*)src->imageData+row*src->width;//获得灰度值数据指针for (size_t cols=0;cols<width;cols++){int intensity=ptr[cols];printf("%03d  ",intensity);}printf("\n");}}

图像灰度，均值，指纹，方差

unsigned int getAverageWithPrintGrayScale(IplImage *src,bool printflag){unsigned int average=0 ;int width=src->width;//图片宽度int height = src->height;//图片高度// 打印图像灰度for (size_t row=0;row<height;row++){uchar* ptr = (uchar*)src->imageData+row*src->width;//获得灰度值数据指针for (size_t cols=0;cols<width;cols++){int intensity=ptr[cols];if(printflag)printf("%03d  ",intensity);average +=intensity ;}if(printflag)printf("\n");}average /= width*height;if(printflag)printf("average:%d  \n",average);return average ;}void  getFingerPrint(IplImage *src,unsigned int average ,bool printflag){int width=src->width;//图片宽度int height = src->height;//图片高度// 打印图像指纹for (size_t row=0;row<height;row++){uchar* ptr = (uchar*)src->imageData+row*src->width;//获得灰度值数据指针for (size_t cols=0;cols<width;cols++){int intensity= ( ptr[cols] > average) ? 1 : 0 ;printf("%d  ",intensity);}printf("\n");}}float getVariance(IplImage *src,unsigned int average,bool printflag){int width=src->width;//图片宽度int height = src->height;//图片高度//求图像方差float variance=0 ;int val =0 ; int tmp =0 ;for (size_t row=0;row<height;row++){uchar* ptr = (uchar*)src->imageData+row*src->width;//获得灰度值数据指针for (size_t cols=0;cols<width;cols++){val = ptr[cols] ;tmp = ( val- average)*( val- average) ;//printf("%03d %d",ptr[cols],tmp);variance = variance + (float)tmp ;//printf(" v:%f **",variance);}//printf("\n");}//printf("varianceALL:%f \n",variance);variance/=width*height ;//printf("varianceOne:%f \n",variance);variance = sqrtf(variance);if(printflag)printf("variance:%f \n",variance);return variance ;}