图像处理   分配与释放图像空间   分配图像空间: IplImage* cvCreateImage(CvSize size, int depth, int channels);   size:   cvSize(width,height);   depth: IPL_DEPTH_8U, IPL_DEPTH_8S, IPL_DEPTH_16U,          IPL_DEPTH_16S, IPL_DEPTH_32S, IPL_DEPTH_32F, IPL_DEPTH_64F   channels: 1, 2, 3 or 4.      注意数据为交叉存取.彩色图像的数据编排为b0 g0 r0 b1 g1 r1 ... 举例: // 分配一个单通道字节图像IplImage* img1=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1); // 分配一个三通道浮点图像IplImage* img2=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);   释放图像空间: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1); cvReleaseImage(&img);   复制图像: IplImage* img1=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1); IplImage* img2;img2=cvCloneImage(img1);   设定/获取兴趣区域: void   cvSetImageROI(IplImage* image, CvRect rect);void   cvResetImageROI(IplImage* image);vRect cvGetImageROI(const IplImage* image);大部分OpenCV函数都支持ROI.   设定/获取兴趣通道: void cvSetImageCOI(IplImage* image, int coi); // 0=allint cvGetImageCOI(const IplImage* image);大部分OpenCV函数暂不支持COI.     读取存储图像   从文件中载入图像:    IplImage* img=0;    img=cvLoadImage(fileName);   if(!img) printf("Could not load image file: %s\n",fileName);   Supported image formats: BMP, DIB, JPEG, JPG, JPE, PNG, PBM, PGM, PPM,                            SR, RAS, TIFF, TIF 载入图像默认转为3通道彩色图像. 如果不是，则需加flag:    img=cvLoadImage(fileName,flag);   flag: >0 载入图像转为三通道彩色图像         =0 载入图像转为单通道灰度图像         <0 不转换载入图像(通道数与图像文件相同).   图像存储为图像文件:    if(!cvSaveImage(outFileName,img)) printf("Could not save: %s\n",outFileName); 输入文件格式由文件扩展名决定.     存取图像元素   假设需要读取在i行j列像点的第k通道. 其中, 行数i的范围为[0, height-1], 列数j的范围为[0, width-1], 通道k的范围为[0, nchannels-1].   间接存取: (比较通用, 但效率低, 可读取任一类型图像数据)   对单通道字节图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);CvScalar s;s=cvGet2D(img,i,j); // get the (i,j) pixel valueprintf("intensity=%f\n",s.val[0]);s.val[0]=111;cvSet2D(img,i,j,s); // set the (i,j) pixel value   对多通道浮点或字节图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);CvScalar s;s=cvGet2D(img,i,j); // get the (i,j) pixel valueprintf("B=%f, G=%f, R=%f\n",s.val[0],s.val[1],s.val[2]);s.val[0]=111;s.val[1]=111;s.val[2]=111;cvSet2D(img,i,j,s); // set the (i,j) pixel value     直接存取: (效率高, 但容易出错)   对单通道字节图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);((uchar *)(img->imageData + i*img->widthStep))[j]=111;   对多通道字节图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);((uchar *)(img->imageData + i*img->widthStep))[j*img->nChannels + 0]=111; // B((uchar *)(img->imageData + i*img->widthStep))[j*img->nChannels + 1]=112; // G((uchar *)(img->imageData + i*img->widthStep))[j*img->nChannels + 2]=113; // R   对多通道浮点图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 0]=111; // B((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 1]=112; // G((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 2]=113; // R     用指针直接存取 : (在某些情况下简单高效)   对单通道字节图像: IplImage* img   = cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);int height      = img->height;int width       = img->width;int step        = img->widthStep/sizeof(uchar);uchar* data     = (uchar *)img->imageData;data[i*step+j] = 111;   对多通道字节图像: IplImage* img   = cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);int height      = img->height;int width       = img->width;int step        = img->widthStep/sizeof(uchar);int channels    = img->nChannels;uchar* data     = (uchar *)img->imageData;data[i*step+j*channels+k] = 111;   对单通道浮点图像(假设用4字节调整): IplImage* img   = cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);int height      = img->height;int width       = img->width;int step        = img->widthStep/sizeof(float);int channels    = img->nChannels;float * data     = (float *)img->imageData;data[i*step+j*channels+k] = 111;       使用 c++ wrapper 进行直接存取: (简单高效)   对单/多通道字节图像，多通道浮点图像定义一个 c++ wrapper: template<class T> class Image{   private:   IplImage* imgp;   public:   Image(IplImage* img=0) {imgp=img;}   ~Image(){imgp=0;}   void operator=(IplImage* img) {imgp=img;}   inline T* operator[](const int rowIndx) {     return ((T *)(imgp->imageData + rowIndx*imgp->widthStep));}};typedef struct{   unsigned char b,g,r;} RgbPixel;typedef struct{   float b,g,r;} RgbPixelFloat;typedef Image<RgbPixel>        RgbImage;typedef Image<RgbPixelFloat>   RgbImageFloat;typedef Image<unsigned char>   BwImage;typedef Image<float>           BwImageFloat;   单通道字节图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);BwImage imgA(img);imgA[i][j] = 111;   多通道字节图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);RgbImage   imgA(img);imgA[i][j].b = 111;imgA[i][j].g = 111;imgA[i][j].r = 111;   多通道浮点图像: IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);RgbImageFloat imgA(img);imgA[i][j].b = 111;imgA[i][j].g = 111;imgA[i][j].r = 111;       图像转换   转为灰度或彩色字节图像: cvConvertImage(src, dst, flags=0);   src = float/byte grayscale/color image   dst = byte grayscale/color image   flags = CV_CVTIMG_FLIP      (flip vertically)           CV_CVTIMG_SWAP_RB   (swap the R and B channels)   转换彩色图像为灰度图像:   使用OpenCV转换函数: cvCvtColor(cimg,gimg,CV_BGR2GRAY); // cimg -> gimg   直接转换: for(i=0;i<cimg->height;i++) for(j=0;j<cimg->width;j++)    gimgA[i][j]= (uchar)(cimgA[i][j].b*0.114 +                         cimgA[i][j].g*0.587 +                         cimgA[i][j].r*0.299);   颜色空间转换:  cvCvtColor(src,dst,code); // src -> dst   code     = CV_<X>2<Y>   <X>/<Y> = RGB, BGR, GRAY, HSV, YCrCb, XYZ, Lab, Luv, HLSe.g.: CV_BGR2GRAY, CV_BGR2HSV, CV_BGR2Lab     绘图命令   画长方体: // 用宽度为1的红线在(100,100)与(200,200)之间画一长方体cvRectangle(img, cvPoint(100,100), cvPoint(200,200), cvScalar(255,0,0), 1);   画圆: // 在(100,100)处画一半径为20的圆,使用宽度为1的绿线cvCircle(img, cvPoint(100,100), 20, cvScalar(0,255,0), 1);   画线段: // 在(100,100)与(200,200)之间画绿色线段，宽度为1cvLine(img, cvPoint(100,100), cvPoint(200,200), cvScalar(0,255,0), 1);   画一组线段: CvPoint   curve1[]={10,10,   10,100,   100,100,   100,10};CvPoint   curve2[]={30,30,   30,130,   130,130,   130,30,   150,10};CvPoint* curveArr[2]={curve1, curve2};int       nCurvePts[2]={4,5};int       nCurves=2;int       isCurveClosed=1;int       lineWidth=1;cvPolyLine(img,curveArr,nCurvePts,nCurves,isCurveClosed,cvScalar(0,255,255),lineWidth);   画内填充色的多边形: cvFillPoly(img,curveArr,nCurvePts,nCurves,cvScalar(0,255,255));   添加文本: CvFont font;double hScale=1.0;double vScale=1.0;int     lineWidth=1;cvInitFont(&font,CV_FONT_HERSHEY_SIMPLEX|CV_FONT_ITALIC, hScale,vScale,0,lineWidth);cvPutText (img,"My comment",cvPoint(200,400), &font, cvScalar(255,255,0)); Other possible fonts: CV_FONT_HERSHEY_SIMPLEX, CV_FONT_HERSHEY_PLAIN,CV_FONT_HERSHEY_DUPLEX, CV_FONT_HERSHEY_COMPLEX,CV_FONT_HERSHEY_TRIPLEX, CV_FONT_HERSHEY_COMPLEX_SMALL,CV_FONT_HERSHEY_SCRIPT_SIMPLEX, CV_FONT_HERSHEY_SCRIPT_COMPLEX,    

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