实现图像的矩形与轮廓

实现图像中最小面积的矩形，适合椭圆形的轮廓。参考代码如下所示：

import cv2
import numpy as np

def thresh_callback(thresh):
    global contours
    edges = cv2.Canny(blur,thresh,thresh*2)
    drawing = np.zeros(img.shape,np.uint8) # Image to draw the contours
    contours,hierarchy = cv2.findContours(edges,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
    for cnt in contours:
        rect = cv2.minAreaRect(cnt) # rect = ((center_x,center_y),(width,height),angle)
        points = cv2.cv.BoxPoints(rect) # Find four vertices of rectangle from above rect
        points = np.int0(np.around(points)) # Round the values and make it integers

        ellipse = cv2.fitEllipse(cnt) # ellipse = ((center),(width,height of bounding rect), angle)
        
        cv2.drawContours(drawing,[cnt],0,(0,255,0),2) # draw contours in green color
        cv2.ellipse(drawing,ellipse,(0,0,255),2) # draw ellipse in red color
        cv2.polylines(drawing,[points],True,(255,0,0),2)# draw rectangle in blue color

        cv2.imshow('output',drawing)
        cv2.imshow('input',img)

img = cv2.imread('Test.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray,(5,5),0)

cv2.namedWindow('input')

thresh = 200
max_thresh = 255

cv2.createTrackbar('canny thresh:','input',thresh,max_thresh,thresh_callback)

thresh_callback(200)

if cv2.waitKey(0) == 27:
    cv2.destroyAllWindows()

输出结果：

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