如何在大量矩形（OpenCV、Python）中选择车牌的右边框

Question

标题相当混乱，因此我将在下面解释我的问题：

我想用OpenCV和Python检测车牌，下面是我的代码：

img = cv2.imread('C:/Users/ACER/Downloads/BikePlate3K/plate_train_2K/image_1703.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) #Grayscale

kernel = np.ones((5,5),np.uint8)

# Dilation
dilation = cv2.dilate(gray,kernel,iterations = 1)

#Edge detection
edges = cv2.Canny(dilation, 120, 560, 1) #120 255

squareKern = cv2.getStructuringElement(cv2.MORPH_RECT, (3, 3))
light = cv2.morphologyEx(edges, cv2.MORPH_CLOSE, squareKern)
light = cv2.threshold(light, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)[1]

thresh = cv2.bitwise_and(edges, edges, mask=light)

rectKern = cv2.getStructuringElement(cv2.MORPH_RECT, (4, 3))
closing = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, rectKern)

cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]

for c in cnts:
  x, y, w, h = cv2.boundingRect(c)
  cv2.rectangle(img, (x, y), (x + w, y + h), (255, 0, 0), 2)

cv2.imshow("Dilation", dilation)
cv2.imshow("Edges", edges)
cv2.imshow("Image", img)
cv2.waitKey(0)

这是我画出每个检测到的轮廓后的结果

所以问题是，我怎么才能只画一个正确的矩形（限制车牌）

（我提出了一些解决方案，比如找到最大的轮廓，但并不总是返回正确的轮廓）