OpenCV學習筆記-形態學操作-腐蝕膨脹-開閉運算
阿新 • • 發佈:2019-01-23
一個可以調節引數的形態學例題,用到的自定義核函式為:
IplConvKernel * cvCreateStructuringElementEx(
int cols,
int rows,
int anchor_x,
int anchor_y,
int shape,
int *value=NULL
);
函式中引數cols,rows確定了構造的矩形大小。anchor_x,anchor_y確定了封閉矩形內參考點的橫縱座標。
shape是自定義核的形狀,具體為
1.CV_SHAPE_RECT 核是矩形
2.CV_SHAPE_CROSS 核是勺子交叉形
3.CV_SHAPE_ELLIPSE 核是橢圓形
4.CV_SHAPE_CUSTOM 核是使用者自定義型別
其釋放函式為
void cvReleaseStructuringElement( IplConvKernel **element);
例項程式碼如下:
#include <cv.h> #include <highgui.h> #include <stdlib.h> #include <stdio.h> IplImage* src = 0; IplImage* dst = 0; IplConvKernel* element = 0; int element_shape = CV_SHAPE_RECT; //the address of variable which receives trackbar position update int max_iters = 10; int open_close_pos = 0; int erode_dilate_pos = 0; // callback function for open/close trackbar void OpenClose(int pos) { int n = open_close_pos - max_iters; int an = n > 0 ? n : -n; element = cvCreateStructuringElementEx( an*2+1, an*2+1, an, an, element_shape, 0 ); if( n < 0 ) { cvErode(src,dst,element,1); cvDilate(dst,dst,element,1); } else { cvDilate(src,dst,element,1); cvErode(dst,dst,element,1); } cvReleaseStructuringElement(&element); cvShowImage("Open/Close",dst); } // callback function for erode/dilate trackbar void ErodeDilate(int pos) { int n = erode_dilate_pos - max_iters; int an = n > 0 ? n : -n; element = cvCreateStructuringElementEx( an*2+1, an*2+1, an, an, element_shape, 0 ); if( n < 0 ) { cvErode(src,dst,element,1); } else { cvDilate(src,dst,element,1); } cvReleaseStructuringElement(&element); cvShowImage("Erode/Dilate",dst); } int main( int argc, char** argv ) { char* filename = argc == 2 ? argv[1] : (char*)"baboon.jpg"; if( (src = cvLoadImage(filename,1)) == 0 ) return -1; printf( "Hot keys: \n" "\tESC - quit the program\n" "\tr - use rectangle structuring element\n" "\te - use elliptic structuring element\n" "\tc - use cross-shaped structuring element\n" "\tENTER - loop through all the options\n" ); dst = cvCloneImage(src); //create windows for output images cvNamedWindow("Open/Close",1); cvNamedWindow("Erode/Dilate",1); open_close_pos = erode_dilate_pos = max_iters; cvCreateTrackbar("iterations", "Open/Close",&open_close_pos,max_iters*2+1,OpenClose); cvCreateTrackbar("iterations", "Erode/Dilate",&erode_dilate_pos,max_iters*2+1,ErodeDilate); for(;;) { int c; OpenClose(open_close_pos); ErodeDilate(erode_dilate_pos); c = cvWaitKey(0); if( (char)c == 27 ) break; if( (char)c == 'e' ) element_shape = CV_SHAPE_ELLIPSE; else if( (char)c == 'r' ) element_shape = CV_SHAPE_RECT; else if( (char)c == 'c' ) element_shape = CV_SHAPE_CROSS; else if( (char)c == '\n' ) element_shape = (element_shape + 1) % 3; } //release images cvReleaseImage(&src); cvReleaseImage(&dst); //destroy windows cvDestroyWindow("Open/Close"); cvDestroyWindow("Erode/Dilate"); return 0; }
執行結果圖為:
說明:
在此例題中開運算和閉運算都是通過腐蝕-膨脹來實現的,而在OpenCV中有封裝好的開閉運算可以直接呼叫。該函式為
void cvMorphologyEx(
const CvArr * src,
CvArr *dst,
CvArr *temp,
IplConvKernel *element,
int operation,
int iterations=1
)
參考資料:
2.學習OpenCV,於仕祺,劉瑞禎,清華大學出版社,134-139