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OpenCV-轮廓周围绘制矩形框以及圆形框

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步骤： OpenCV-轮廓周围绘制矩形框以及圆形框
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API:
功能：近似于曲线的或与另一曲线/多边形的多边形用更少的顶点，使得它们之间的距离是小于或等于指定的精度
approxCurve=cv.approxPolyDP(curve, epsilon, closed[, approxCurve])
OpenCV-轮廓周围绘制矩形框以及圆形框
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矩形：
BoundingRect是说，用一个最小的矩形，把找到的形状包起来。还有一个带旋转的矩形，面积会更小
minAreaRect函数返回矩形的中心点坐标，长宽，旋转角度[-90,0)，当矩形水平或竖直时均返回-90
OpenCV-轮廓周围绘制矩形框以及圆形框
文章图片

圆：
OpenCV-轮廓周围绘制矩形框以及圆形框
文章图片

#include #include #include using namespace std; using namespace cv; Mat src, gray_src, dst; const char* output_title = "绘制结果"; const char* gray_title = "灰度图像"; int threshold_value = https://www.it610.com/article/50; int threshold_max = 255; void threshold_Demo(int, void*); //在轮廓周围绘制矩形和圆形 int main(int argc, char ** argv) { src = imread("E://VS-pro//images//text.bmp"); if (!src.data) { printf("can not find .. \n"); return -1; } imshow("原图", src); //变灰度 cvtColor(src, gray_src, COLOR_BGR2GRAY); blur(gray_src, gray_src, Size(3, 3), Point(-1, -1)); imshow(gray_title, gray_src); createTrackbar("threshold value: ", gray_title, &threshold_value, threshold_max, threshold_Demo); threshold_Demo(0, 0); waitKey(0); return 0; }void threshold_Demo(int, void*) { Mat bin_src; //转换为二值图像 threshold(gray_src, bin_src, threshold_value, threshold_max, THRESH_BINARY); imshow("二值图像", bin_src); vector contours; //放轮廓点 vector hierachy; //图像的拓扑结构 //找轮廓 findContours(bin_src, contours, hierachy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(-1, -1)); //根据轮廓点找最小矩形和圆 vector contours_ploy(contours.size()); //存放绘制矩形的点 vector ploy_rects(contours.size()); vector【OpenCV-轮廓周围绘制矩形框以及圆形框】 ccs(contours.size()); //放圆心 vector radius(contours.size()); //放半径 vector minRects(contours.size()); vector myellipse(contours.size()); for (size_t i = 0; i < contours.size(); i++) { approxPolyDP(Mat(contours[i]), contours_ploy[i], 3, true); //减少多边形轮廓点数 ploy_rects[i] = boundingRect(contours_ploy[i]); //取矩形 minEnclosingCircle(contours_ploy[i], ccs[i], radius[i]); //圆//另一种方法 if (contours_ploy[i].size() > 5) { myellipse[i] = fitEllipse(contours_ploy[i]); minRects[i] = minAreaRect(contours_ploy[i]); } } //绘制 Mat drawImg; RNG rng(12345); // draw it drawImg = Mat::zeros(src.size(), src.type()); Point2f pts[4]; for (size_t t = 0; t < contours.size(); t++) { Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255)); //rectangle(drawImg, ploy_rects[t], color, 2, 8); //circle(drawImg, ccs[t], radius[t], color, 2, 8); if (contours_ploy[t].size() > 5) { ellipse(drawImg, myellipse[t], color, 1, 8); //画圆 minRects[t].points(pts); for (int r = 0; r < 4; r++) { line(drawImg, pts[r], pts[(r + 1) % 4], color, 1, 8); //画矩形四条边 } } } imshow(output_title, drawImg); }

OpenCV-轮廓周围绘制矩形框以及圆形框
文章图片

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