opencv-在图像中绘制轮廓 [英] opencv - plot contours in an image

问题描述

我正在尝试在图像周围绘制轮廓。我可以看到已找到轮廓，但无法绘制轮廓。轮廓的颜色似乎是两种（黑色和白色）颜色之一。

I am trying to draw contour around an image. I can see that contours being found but I am not able to draw the outline. The color of the contour seem to be either of the two (black and white) colors.

import cv2
import numpy as np
import matplotlib.pyplot as plt
from skimage import io
%matplotlib inline
im = io.imread('http://matlabtricks.com/images/post-35/man.png')
plt.imshow(im)
imgray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
plt.figure()
plt.imshow(imgray)

#Contoured image
ret,thresh = cv2.threshold(imgray, 120,255,cv2.THRESH_BINARY)
image, contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
c_img = cv2.drawContours(image, contours, -1, (0, 255, 0), 1)
plt.figure()
plt.imshow(c_img)

推荐答案

您需要绘制原始图像，而不是 findContuors（）返回的图像。以下作品。

You need to draw on the original image, not on the one returned from findContuors(). The following works.

# Contoured image
ret,thresh = cv2.threshold(imgray, 120,255,cv2.THRESH_BINARY)
contours = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)[-2]
for contour in contours:
   cv2.drawContours(im, contour, -1, (0, 255, 0), 3)
plt.figure()
plt.imshow(im)

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