Python错误：没有足够的值来解包（预期为3，得到2）

Question

这是我的代码：

import cv2
import numpy as np
import imutils
import argparse

cap = cv2.VideoCapture(0)

while True :
    _,frame = cap.read()
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    lower_blue = np.array([150,104,90])
    upper_blue = np.array ([176,161,157])
    mask = cv2.inRange(hsv, lower_blue, upper_blue)
    

    cv2.imshow ("frame", frame)
    cv2.imshow("mask", mask)

    _, contours, _ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
    cv2.drawContours(frame, contours)


    key = cv2.waitKey(1)
    if key ==27 :
        break

cap.release()
cv2.destroyAllWindows()

运行上述代码后，显示此错误：

Traceback (most recent call last): File "D:/1Kuliah/Kegiatan Kuliah/Roboboat/ROBONATION JADI!!/kkctbn/coba.py", line 20, in _, contours, _ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)

ValueError: not enough values to unpack (expected 3, got 2)

我想问题出在等高线的值上，但我无法解决，请帮助我

Answer 1

您可以修改调用cv2.findContours的行：

contours, _ = cv2.findContours( # Just extract return values 
                                # into two variables
    mask, 
    cv2.RETR_TREE,         
    cv2.CHAIN_APPROX_NONE
)
cv2.drawContours(frame, contours)