Detailed explanation of examples of adding Chinese characters to PILLOW pictures

Index

• Brief description

• Preparation

• Example

• Rendering

• Conclusion

Brief description

I think when using opencv2 or 3 To add Chinese text to the picture, you need to download the Freetype library, compile it and link it to the opencv library to output Chinese. Most of the tutorials on inserting Chinese into pictures on the Internet are still win+vs configuration tutorials. For people like me who have an environment under win and an environment under linux, it is undoubtedly a bit troublesome to synchronize the code. Fortunately, there is an alternative, which is the example below: pillow.

Preparation

1. pillow installation
   couldn’t be simpler, you can install it as follows:
   pip install pillow
   Or
   conda install pillow

2. The next font library that supports Chinese
   Search keywords: ttf font. Download a font style library you like. The suffix of the file is generally ttf. I downloaded a Microsoft Yahei library. The file name is msyh.ttf

Example

First create a new python file: draw_chinese .py. For sample code ipython-notebook style, please go here
1. Import library

import cv2from PIL import Image,ImageFont,ImageDrawfrom matplotlib.pyplot import imshowimport numpy as np

Image: An instance of an object represents an image , you can perform some size transformation and affine transformation operations
ImageFont: Used to load the font library file downloaded in the preparation stage
ImageDraw: Based on the image object, create an An object that can draw lines and paste text on Image instances.
2. Create a picture

img = Image.new(mode="RGB",size=(400,150),color=(120,20,20))
#或者从numpy对象中创建也行。可以把opencv的图片转为numpy，通过numpy连接两个图像处理库。
#img = Image.fromarray(numpy_object)
img.show()

3. Load the font library

path_to_ttf = r'data/msyh.ttf'
font = ImageFont.truetype(path_to_ttf, size=25)
#size 确定一个汉字的大小

4. Create a new canvas

draw = ImageDraw.Draw( img )

6 .Do whatever you want on the canvas

draw.text(xy=(30,30),text='Hello，南墙已破！',font=font)
img.show()
#当然也可以把这个写好字的图片转换回numpy
#img2array = np.asanyarray(img)

Rendering

##Conclusion

This method does not require you to download and compile the Freetype library yourself. The installation of pillow is also very simple. The written code can be used in both python2 and python3. Cross-platform is fine too. It can be said that Curve has solved the problem that opencv does not natively support Chinese fonts.

pillow is a library that can do some of the work of opencv. So far, I have found a setting that is commonly used but does not exist in pillow. When drawing a rectangular frame, you cannot set the width of the rectangular frame edges. You need to implement it manually: each time based on the original Increase or decrease the coordinate position of a pixel to repeat the frame to achieve the effect of increasing the width. Opencv only needs to give a width parameter.

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