opencv 9 -- 轮廓 性质

x,y,w,h = cv2.boundingRect(cnt)
aspect_ratio = float(w)/h

area = cv2.contourArea(cnt)
x,y,w,h = cv2.boundingRect(cnt)
rect_area = w*h
extent = float(area)/rect_area

area = cv2.contourArea(cnt)
hull = cv2.convexHull(cnt)
hull_area = cv2.contourArea(hull)
solidity = float(area)/hull_area

area = cv2.contourArea(cnt)
equi_diameter = np.sqrt(4*area/np.pi)

(x,y),(MA,ma),angle = cv2.fitEllipse(cnt)

mask = np.zeros(imgray.shape,np.uint8) 
# 这里一定要使用参数-1, 绘制填充的的轮廓
cv2.drawContours(mask,[cnt],0,255,-1)
//方法一 bumpy方法
pixelpoints = np.transpose(np.nonzero(mask))
//方法二 opencv方法
#pixelpoints = cv2.findNonZero(mask)

min_val, max_val, min_loc, max_loc = cv2.minMaxLoc(imgray,mask = mask)

mean_val = cv2.mean(im,mask = mask)

leftmost = tuple(cnt[cnt[:,:,0].argmin()][0])
rightmost = tuple(cnt[cnt[:,:,0].argmax()][0])
topmost = tuple(cnt[cnt[:,:,1].argmin()][0])
bottommost = tuple(cnt[cnt[:,:,1].argmax()][0])