【图像处理】opencv绘制轮廓的外接矩形和圆

1、把图片转化为二值图片：

img1 = cv2.imread('0.png',0)

_,thresh = cv2.threshold(img1,200,255,0)

2、检测轮廓，并绘制轮廓：

img10 = cv2.imread('0.png')

image,contours,_ = cv2.findContours(thresh,2,1)

for c in contours[1:]:

    cv2.drawContours(img10,[c],0,(0,0,255),2)

3、绘制外接矩形，要横平竖直那种：

for c in contours[1:]:

    x, y, w, h = cv2.boundingRect(c)  # 外接矩形

    cv2.rectangle(img10,(x,y),(x+w,y+h),(0,255,0),2)

4、绘制最小的外接矩形：

for c in contours[1:]:

    rect = cv2.minAreaRect(c)

    box = np.int0(cv2.boxPoints(rect))

    cv2.drawContours(img10,[box],0,(255,0,0),2)

5、绘制最小外接圆：

for c in contours[1:]:

    (x, y), radius = cv2.minEnclosingCircle(c)

    (x, y, radius) = np.int0((x,y,radius))

    cv2.circle(img10, (x,y),radius,(255,255,0),2)

6、用轮廓数据来拟合椭圆：

for c in contours[1:]:

    ellipse = cv2.fitEllipse(c)

    cv2.ellipse(img10, ellipse,(255,0,255),2)

这不是外接椭圆。