Want to find contours -> ValueError: not enough values to unpack (expected 3, got 2), this appears

Question

我的简单Python代码是这样的

import cv2

img=cv2.imread('Materials/shapes.png')

blur=cv2.GaussianBlur(img,(3,3),0)
gray=cv2.cvtColor(blur,cv2.COLOR_BGR2GRAY)
returns,thresh=cv2.threshold(gray,80,255,cv2.THRESH_BINARY)

ret,contours,hierachy=cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

for cnt in contours:

    area=cv2.contourArea(cnt) #contour area
    
    if (area>1220):
        cv2.drawContours(img,[cnt],-1,(0,255,0),2)
        cv2.imshow('RGB',img)
        cv2.waitKey(1000)
        print(len(cnt))

import numpy as np

contours=np.array(contours)

print(contours)

这很好用。但最近我什至没有做任何改变。这是扔给我的

ret,contours,hierachy=cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

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

Answer 1

函数 cv2.findContours() 已更改为 return 只有轮廓和层次结构而不是 ret

您应该将其更改为：

contours,hierachy=cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

Answer 2

在 this python 代码示例中进行了很好的解释，使代码不受版本影响的最佳方法是使用以下语法：

# check OpenCV version
major = cv2.__version__.split('.')[0]
if major == '3':
    ret, contours, hierarchy = cv2.findContours(im.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
else:
    contours, hierarchy = cv2.findContours(im.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

这为您提供了一个代码，可以运行在最新版本或旧版本的 OpenCV 上。

Want to find contours -> ValueError: not enough values to unpack (expected 3, got 2), this appears

Want to find contours -> ValueError: not enough values to unpack (expected 3, got 2), this appears

python

python-3.x

opencv-contour