问题描述
我是python初学者.我正在尝试运行此代码:
I am a python beginner . I was trying to run this code :
#applying closing function
kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (7, 7))
closed = cv2.morphologyEx(th3, cv2.MORPH_CLOSE, kernel)
#finding_contours
(cnts, _) = cv2.findContours(closed.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
for c in cnts:
peri = cv2.arcLength(c, True)
approx = cv2.approxPolyDP(c, 0.02 * peri, True)
cv2.drawContours(frame, [approx], -1, (0, 255, 0), 2)
当我召唤mask.py时,我得到了这个ValueError:
when I summon the mask.py I got this ValueError :
Traceback (most recent call last):
File "mask.py", line 22, in <module>
(cnts, _) = cv2.findContours(closed.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
ValueError: too many values to unpack
此代码有什么问题?
推荐答案
似乎您正在使用OpenCV版本3.x,同时编写了用于2.x分支的代码.在这两个分支之间有一些API更改.由于您使用的是Python,因此您将获得方便的帮助-请确保将其与文档一起使用.
It appears that you're using OpenCV version 3.x, while writing code intended for the 2.x branch. There were some API changes between those two branches. Since you're using Python, you have a handy help available -- make sure to use it, along with the documentation.
OpenCV 2.x:
OpenCV 2.x:
>>> import cv2
>>> help(cv2.findContours)
Help on built-in function findContours in module cv2:
findContours(...)
findContours(image, mode, method[, contours[, hierarchy[, offset]]]) -> contours, hierarchy
OpenCV 3.x:
OpenCV 3.x:
>>> import cv2
>>> help(cv2.findContours)
Help on built-in function findContours:
findContours(...)
findContours(image, mode, method[, contours[, hierarchy[, offset]]]) -> image, contours, hierarchy
这意味着在脚本中,使用OpenCV 3.x时调用findContours
的正确方法将类似于
This means that in your script the correct way to call findContours
when using OpenCV 3.x would be something like
(_, cnts, _) = cv2.findContours(closed.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
更新(2018年12月)
在OpenCV 4.x中, findContours
仅返回2个值.
In OpenCV 4.x, findContours
returns 2 values only.
>>> help(cv2.findContours)
Help on built-in function findContours:
findContours(...)
findContours(image, mode, method[, contours[, hierarchy[, offset]]]) -> contours, hierarchy
. @brief Finds contours in a binary image.
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