OpenCV Python车辆计数程序报错：int与NoneType无法执行+运算

我正在开发基于OpenCV Python的车辆计数程序，但尝试为车辆绘制矩形框时出现错误，请求帮助解决：

ret, frame1 = capVideo.read()
gray = cv2.cvtColor(frame1, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (3,3),5)
img_sub = carAlgo.apply(blur)
dillat = cv2.dilate(img_sub, np.ones((5,5)))
kernal = cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(5,5))
dillData = cv2.morphologyEx(dillat, cv2.MORPH_CLOSE, kernal)
dillData = cv2.morphologyEx(dillData, cv2.MORPH_CLOSE, kernal)
countVehcal, h= ( cv2.findContours(dillData, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE))

#If we pass dilladat in (imshow then it will provide grey effect)
#to draw a line on the videoView
cv2.line(frame1,(25, lineLength), (1400, lineLength), (255,127,0),3)

for (i,c) in enumerate (countVehcal):
    #w=width , z= hight;
    (x,y,w,h) = cv2.boundingRect(c)
    vd_count = (w>=min_rectangle_with) and (h>=min_rectangle_hight)
    if not vd_count:
        continue

cv2.rectangle(frame1, (x,y), (x+w, y+h), (0,0,255), 2)
cv2.imshow('Vehical Count', frame1)

出现的错误信息：

Traceback (most recent call last):
  File "D:\Vehical project\main.py", line 42, in <module>
    cv2.rectangle(frame1, (x,y), (x+w, y+h), (0,0,255), 2)
TypeError: unsupported operand type(s) for +: 'int' and 'NoneType'

错误原因 #

• 循环逻辑错误：绘制矩形的代码写在for循环外部，导致只有最后一个轮廓的变量会被使用；如果所有轮廓都因尺寸不达标被continue跳过，x,y,w,h会处于未定义或None状态，触发运算错误。
• 变量作用域问题：x,y,w,h是循环内的局部变量，循环结束后若没有符合条件的轮廓，这些变量无有效值。
• 拼写错误：代码中min_rectangle_with应为min_rectangle_width，可能导致尺寸判断逻辑失效。

修复步骤 #

1. 将绘制矩形的代码移到循环内部：每找到一个符合尺寸要求的车辆轮廓，立即绘制对应矩形框。
2. 添加帧读取有效性判断：避免视频读取失败时后续代码报错。
3. 修正变量名拼写：确保尺寸判断的变量名正确。

修复后的代码示例：

ret, frame1 = capVideo.read()
# 先判断是否成功读取帧
if not ret:
    print("无法读取视频帧")
    exit()

gray = cv2.cvtColor(frame1, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (3,3),5)
img_sub = carAlgo.apply(blur)
dillat = cv2.dilate(img_sub, np.ones((5,5)))
kernal = cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(5,5))
dillData = cv2.morphologyEx(dillat, cv2.MORPH_CLOSE, kernal)
dillData = cv2.morphologyEx(dillData, cv2.MORPH_CLOSE, kernal)
# 适配OpenCV常见版本的findContours返回值
countVehcal, h = cv2.findContours(dillData, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

# 绘制计数线
cv2.line(frame1,(25, lineLength), (1400, lineLength), (255,127,0),3)

for (i,c) in enumerate(countVehcal):
    (x,y,w,h) = cv2.boundingRect(c)
    # 修正变量名拼写错误
    vd_count = (w >= min_rectangle_width) and (h >= min_rectangle_hight)
    if not vd_count:
        continue
    # 移到循环内，每符合条件就绘制矩形
    cv2.rectangle(frame1, (x,y), (x+w, y+h), (0,0,255), 2)

cv2.imshow('Vehicle Count', frame1)

额外提示 #

• 确保min_rectangle_width和min_rectangle_hight（建议统一改成min_rectangle_height）已被正确赋值，比如设置为min_rectangle_width = 40、min_rectangle_height = 80这类符合场景的数值。
• 若使用OpenCV 3.x版本，cv2.findContours会返回三个值：image, contours, hierarchy，需调整接收变量避免解包错误。

内容的提问来源于stack exchange，提问作者Anurag Bca