如何在Python中使用OpenCV检测和绘制轮廓? [英] How to detect and draw contours using OpenCV in Python?

问题描述

我编写了以下代码来检测和绘制轮廓:

I wrote the following code to detect and draw contours:

img = cv2.imread('test2.tif');

if not img is None:
    imgray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY);
    ret,thresh = cv2.threshold(imgray,127,255,0);
    contours,hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE);

    #draw a three pixel wide outline 
    cv2.drawContours(img,contours,-1,(0,255,0),3);

这是我收到的错误:

回溯(最近通话最近): 文件"C:/Users/R.K.singh/Desktop/图像处理/intro-to-contours.py"，第10行，在 等高线，层次结构= cv2.findContours(thresh，cv2.RETR_TREE，cv2.CHAIN_APPROX_SIMPLE); ValueError:太多值无法解压缩

Traceback (most recent call last): File "C:/Users/R.K.singh/Desktop/Image processing/intro-to-contours.py", line 10, in contours,hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE); ValueError: too many values to unpack

怎么了?我正在使用Python 2.7和OpenCV 3.1.0

What is wrong? I am using Python 2.7 and OpenCV 3.1.0

推荐答案

为了强调Selchuk的观点，涉及OpenCV 3.x的语法有所改变.当涉及到cv2.findContours时，它具有不同的返回值.它返回以下image, contours, hierarchy.

In order to emphasize Selchuk's point, the syntax involving OpenCV 3.x has changed a little bit. It has a different return value when it comes to cv2.findContours. It returns the following image, contours, hierarchy.

但是，早期版本的OpenCV仅返回contours, hierarchy.他们不返回图像.

Previous versions of OpenCV, however, return only contours, hierarchy. They do not return the image.

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