基本上你需要检测圆形。你看过cvHoughCircles()
吗?你可以使用它吗?
这个页面提供了关于如何用OpenCV检测东西的好资料。你可能更感兴趣第2.5节。
这是我刚写的一个小演示,用于检测这张图片中的硬币。希望你能从代码中获得一些有益的部分。
输入:
![input img](https://istack.dev59.com/hoD2b.webp)
输出:
![output opencv img](https://istack.dev59.com/Zfss9.webp)
#include <stdio.h>
#include <cv.h>
#include <highgui.h>
#include <math.h>
int main(int argc, char** argv)
{
IplImage* img = NULL;
if ((img = cvLoadImage(argv[1]))== 0)
{
printf("cvLoadImage failed\n");
}
IplImage* gray = cvCreateImage(cvGetSize(img), IPL_DEPTH_8U, 1);
CvMemStorage* storage = cvCreateMemStorage(0);
cvCvtColor(img, gray, CV_BGR2GRAY);
cvSmooth(gray, gray, CV_GAUSSIAN, 7, 7);
IplImage* canny = cvCreateImage(cvGetSize(img),IPL_DEPTH_8U,1);
IplImage* rgbcanny = cvCreateImage(cvGetSize(img),IPL_DEPTH_8U,3);
cvCanny(gray, canny, 50, 100, 3);
CvSeq* circles = cvHoughCircles(gray, storage, CV_HOUGH_GRADIENT, 1, gray->height/3, 250, 100);
cvCvtColor(canny, rgbcanny, CV_GRAY2BGR);
for (size_t i = 0; i < circles->total; i++)
{
float* p = (float*)cvGetSeqElem(circles, i);
cv::Point center(cvRound(p[0]), cvRound(p[1]));
int radius = cvRound(p[2]);
cvCircle(rgbcanny, center, 3, CV_RGB(0,255,0), -1, 8, 0 );
cvCircle(rgbcanny, center, radius+1, CV_RGB(0,0,255), 2, 8, 0 );
printf("x: %d y: %d r: %d\n",center.x,center.y, radius);
}
cvNamedWindow("circles", 1);
cvShowImage("circles", rgbcanny);
cvSaveImage("out.png", rgbcanny);
cvWaitKey(0);
return 0;
}
检测圆形非常依赖于
cvHoughCircles()
的参数。请注意,本演示中我也使用了Canny算法。