Python matplotlib：如何在图像上绘制矩形
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/37435369/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
matplotlib: how to draw a rectangle on image
提问by KAI ZHAO
How to draw a rectangle on a image, like this:
如何在图像上绘制矩形，如下所示：
import matplotlib.pyplot as plt
from PIL import Image
import numpy as np
im = np.array(Image.open('dog.png'), dtype=np.uint8)
plt.imshow(im)
I don't know what to do the next.
我不知道接下来要做什么。
回答by tmdavison
You can add a Rectanglepatch to the matplotlib Axes.
您可以Rectangle向 matplotlib 轴添加补丁。
For example (using the image from the tutorial here):
例如（使用此处教程中的图像）：
import matplotlib.pyplot as plt
import matplotlib.patches as patches
from PIL import Image
import numpy as np
im = np.array(Image.open('stinkbug.png'), dtype=np.uint8)
# Create figure and axes
fig,ax = plt.subplots(1)
# Display the image
ax.imshow(im)
# Create a Rectangle patch
rect = patches.Rectangle((50,100),40,30,linewidth=1,edgecolor='r',facecolor='none')
# Add the patch to the Axes
ax.add_patch(rect)
plt.show()
回答by Serenity
You need use patches.
你需要使用补丁。
import matplotlib.pyplot as plt
import matplotlib.patches as patches
fig2 = plt.figure()
ax2 = fig2.add_subplot(111, aspect='equal')
ax2.add_patch(
patches.Rectangle(
(0.1, 0.1),
0.5,
0.5,
fill=False # remove background
) )
fig2.savefig('rect2.png', dpi=90, bbox_inches='tight')
回答by James 'Fluffy' Burton
There is no need for subplots, and pyplot can display PIL images, so this can be simplified further:
不需要 subplots，pyplot 可以显示 PIL 图像，因此可以进一步简化：
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle
from PIL import Image
im = Image.open('stinkbug.png')
# Display the image
plt.imshow(im)
# Get the current reference
ax = plt.gca()
# Create a Rectangle patch
rect = Rectangle((50,100),40,30,linewidth=1,edgecolor='r',facecolor='none')
# Add the patch to the Axes
ax.add_patch(rect)
Or, the short version:
或者，简短版本：
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle
from PIL import Image
# Display the image
plt.imshow(Image.open('stinkbug.png'))
# Add the patch to the Axes
plt.gca().add_patch(Rectangle((50,100),40,30,linewidth=1,edgecolor='r',facecolor='none'))
回答by user3731622
From my understanding matplotlibis a plotting library.
根据我的理解matplotlib是一个绘图库。
If you want to change the image data (e.g. draw a rectangle on an image), you could use PIL's ImageDraw, OpenCV, or something similar.
如果您想更改图像数据（例如在图像上绘制矩形），您可以使用PIL 的 ImageDraw、OpenCV或类似的东西。
Here is PIL's ImageDraw method to draw a rectangle.
Here is one of OpenCV's methods for drawing a rectangle.
Your question asked about Matplotlib, but probably should have just asked about drawing a rectangle on an image.
您的问题询问了 Matplotlib，但可能应该询问有关在图像上绘制矩形的问题。
Here is another question which addresses what I think you wanted to know: Draw a rectangle and a text in it using PIL
这是另一个问题，它解决了我认为您想知道的问题： 使用 PIL 在其中绘制一个矩形和一个文本
