opencv OpenCV访问图像像素, 数组元素等方法收集

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 valueo For a multi-channel float (or byte) image: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* Direct access: (Efficient access, but error prone)o For a single-channel byte image:IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);((uchar *)(img->imageData + i*img->widthStep))[j]=111;o For a multi-channel byte image: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; // Ro For a multi-channel float image: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* Direct access using a pointer: (Simplified and efficient access under limiting assumptions)o For a single-channel byte image: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;o For a multi-channel byte image: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;o For a multi-channel float image (assuming a 4-byte alignment):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;* Direct access using a c++ wrapper: (Simple and efficient access)o Define a c++ wrapper for single-channel byte images, multi-channel byte images, and multi-channel float images: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;o For a single-channel byte image:IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);BwImage imgA(img);imgA[i][j] = 111;o For a multi-channel byte image: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;o For a multi-channel float image: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;

from:http://www.opencv.org.cn/forum/viewtopic.php?f=1&t=9176&p=43221&hilit=hq#p35196.  感谢 网友hqhuang1~~