opencv OpenCV访问图像像素, 数组元素等方法收集
opencv OpenCV访问图像像素, 数组元素等方法收集
2017年11月02日
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分类: OPENCV2012-10-08
21:13 104人阅读 收藏 举报
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);
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CvScalar s;
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s=cvGet2D(img,i,j);
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printf("intensity=%f\n",s.val[0]);
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s.val[0]=111;
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cvSet2D(img,i,j,s);
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o For a multi-channel float (or byte) image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);
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CvScalar s;
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s=cvGet2D(img,i,j);
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printf("B=%f, G=%f, R=%f\n",s.val[0],s.val[1],s.val[2]);
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s.val[0]=111;
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s.val[1]=111;
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s.val[2]=111;
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cvSet2D(img,i,j,s);
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* Direct access: (Efficient access, but error prone)
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o For a single-channel byte image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);
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((uchar *)(img->imageData + i*img->widthStep))[j]=111;
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o For a multi-channel byte image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);
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((uchar *)(img->imageData + i*img->widthStep))[j*img->nChannels + 0]=111;
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((uchar *)(img->imageData + i*img->widthStep))[j*img->nChannels + 1]=112;
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((uchar *)(img->imageData + i*img->widthStep))[j*img->nChannels + 2]=113;
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o For a multi-channel float image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);
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((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 0]=111;
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((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 1]=112;
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((float *)(img->imageData + i*img->widthStep))[j*img->nChannels + 2]=113;
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* Direct access using a pointer: (Simplified and efficient access under limiting assumptions)
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o For a single-channel byte image:
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IplImage* img = cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);
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int height = img->height;
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int width = img->width;
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int step = img->widthStep/sizeof(uchar);
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uchar* data = (uchar *)img->imageData;
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data[i*step+j] = 111;
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o For a multi-channel byte image:
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IplImage* img = cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);
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int height = img->height;
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int width = img->width;
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int step = img->widthStep/sizeof(uchar);
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int channels = img->nChannels;
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uchar* data = (uchar *)img->imageData;
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data[i*step+j*channels+k] = 111;
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o For a multi-channel float image (assuming a 4-byte alignment):
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IplImage* img = cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);
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int height = img->height;
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int width = img->width;
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int step = img->widthStep/sizeof(float);
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int channels = img->nChannels;
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float * data = (float *)img->imageData;
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data[i*step+j*channels+k] = 111;
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* Direct access using a c++ wrapper: (Simple and efficient access)
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o Define a c++ wrapper for single-channel byte images, multi-channel byte images, and multi-channel float images:
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template<class T> class Image
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{
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private:
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IplImage* imgp;
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public:
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Image(IplImage* img=0) {imgp=img;}
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~Image(){imgp=0;}
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void operator=(IplImage* img) {imgp=img;}
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inline T* operator[](const int rowIndx) {
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return ((T *)(imgp->imageData + rowIndx*imgp->widthStep));}
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};
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typedef struct{
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unsigned char b,g,r;
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} RgbPixel;
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typedef struct{
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float b,g,r;
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} RgbPixelFloat;
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typedef Image<RgbPixel> RgbImage;
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typedef Image<RgbPixelFloat> RgbImageFloat;
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typedef Image<unsigned char> BwImage;
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typedef Image<float> BwImageFloat;
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o For a single-channel byte image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);
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BwImage imgA(img);
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imgA[i][j] = 111;
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o For a multi-channel byte image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,3);
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RgbImage imgA(img);
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imgA[i][j].b = 111;
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imgA[i][j].g = 111;
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imgA[i][j].r = 111;
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o For a multi-channel float image:
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IplImage* img=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3);
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RgbImageFloat imgA(img);
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imgA[i][j].b = 111;
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imgA[i][j].g = 111;
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imgA[i][j].r = 111;