Table of Contents
Preparation
Create new project
Prepare base image
Add image annotation
Realize automatic line wrapping
Set dynamic text box height
Add text padding
Add pointer
Full code
Conclusion
Home Backend Development Python Tutorial Wrap and Render Multiline Text on Images Using Python&#s Pillow Library

Wrap and Render Multiline Text on Images Using Python&#s Pillow Library

Jan 14, 2025 am 08:59 AM

Python image processing: Pillow library implements automatic line wrapping text annotation

Python has become the leading programming language in the field of image processing with its rich open source libraries. Pillow is one of the commonly used image processing libraries. It is simple, easy to use and has complete documentation. It is often used for operations such as image scaling, cropping, brightness adjustment and annotation.

However, Pillow has a problem with text annotation: when the text exceeds the width of the text box, it will not wrap automatically. The Pillow library itself does not provide this function, and we need to write the logic implementation ourselves.

This tutorial will demonstrate how to use the Pillow library to add a word-wrap text box in Python to achieve correct image text annotation. The final effect is as follows:

Wrap and Render Multiline Text on Images Using Python

The picture above is a screenshot of my Dev.to profile, we will use this as an example to explain. The green text box is the text annotation we added.

Preparation

This tutorial requires you to have basic Python programming knowledge, such as conditional statements (if, else), for loops, etc. You'll also need the following tools and software:

  1. Python3 : Interpreter for running Python scripts.
  2. Pillow: Python image processing library.
  3. Code editor: such as Pycharm, VScode, etc.

Create new project

Follow these steps to create a new project:

A. Create a new folder using terminal/command line:

mkdir image_annotation
Copy after login
Copy after login
Copy after login

B. Use pip to install virtualenv (skip this step if you have already installed it):

pip install virtualenv
Copy after login
Copy after login
Copy after login

C. Switch the working directory to the image_annotation folder:

cd image_annotation
Copy after login
Copy after login

D. Create a new virtual environment:

virtualenv env
Copy after login
Copy after login

E. Activate virtual environment (use command prompt for Windows):

Windows:

.\env\Scripts\activate
Copy after login
Copy after login

Linux/macOS:

source env/bin/activate
Copy after login
Copy after login

F. Use pip to install the Pillow library:

pip install pillow
Copy after login
Copy after login

Open the project in the code editor and create a new Python file named script.py in the project folder.

Prepare base image

The image you want to annotate is the base image. Open and prepare the image using Pillow's ImageDraw module. Write the following code in the script.py file:

from PIL import Image, ImageDraw, ImageFont
image_file = "path_to_image"  # 请替换为您的图片路径

# 打开图像
image = Image.open(image_file)

# 初始化ImageDraw
draw = ImageDraw.Draw(image)
Copy after login

Add image annotation

Pillow can add plain text and text boxes with background filling. The text can be single line or multiple lines. This tutorial focuses on how to add a multi-line text box.

The

ImageDraw.multiline_text() method can add multiple lines of plain text, but no background padding. ImageDraw.rectangle() method can add a text box with background fill.

Add the following code in the script.py file:

mkdir image_annotation
Copy after login
Copy after login
Copy after login

This code sets the text, font, and text box width. The x and y variables represent the starting point of the drawing, and end_x and end_y represent the coordinates of the lower right corner of the text box. The width and height of the text box are 200 and 50 respectively.

The

ImageDraw.rectangle() and ImageDraw.multiline_text() methods are used to draw text boxes and multi-line text respectively. The image.show() method is used to display the processed image. You can save the image using image.save("new_image.png"). The results are as follows:

Wrap and Render Multiline Text on Images Using Python&#s Pillow Library

There is still a problem with the annotation in the picture above, and the multi-line text does not wrap automatically. The next section explains how to solve this problem.

Realize automatic line wrapping

Line break character n is used to specify the line break position. In the previous example, the content after the newline character n will wrap. But in practical applications, the text length is usually dynamic and it is difficult to determine the position of the newline character.

The

attribute of ImageDrawPillow's .textlength() module can calculate the text length and compare it with the text box width to determine the line break position.

Create a new function named script.py at the top of the wrap_text() file (after the import statement), containing the word-wrap logic:

pip install virtualenv
Copy after login
Copy after login
Copy after login

Add the following code after the text, font, max_width variables:

cd image_annotation
Copy after login
Copy after login

Replace the draw.multiline_text() method with the following code:

virtualenv env
Copy after login
Copy after login

Remove newlines from the text n and run the code:

.\env\Scripts\activate
Copy after login
Copy after login

The running result shows that the text still exceeds the height of the text box. While the text automatically adjusts to the text box width, the text box height is fixed, causing the text to overflow.

Set dynamic text box height

The height of the dynamic text box is determined based on the number of text lines. The first step is to change the text box's end_y variable to a dynamic value:

source env/bin/activate
Copy after login
Copy after login

This formula was arrived at after many experiments and it seems to be the best solution for getting dynamic textbox height in this use case. wrapped_linesThe list contains all the lines to be added to the text box, so the length of the list is equal to the total number of lines of the text box.

The results are as follows:

Wrap and Render Multiline Text on Images Using Python&#s Pillow Library

You may need to multiply the total number of rows by different values ​​to get the perfect solution for your use case.

Add text padding

The text is too close to the edge of the text box, affecting readability and style. You can solve this problem by adding padding inside the text box. Add a new script.py variable in the padding file and change the text box size:

pip install pillow
Copy after login
Copy after login

This code allows for spacing between the text and the edges of the text box.

Add pointer

The pointer can conveniently indicate the part of the image that the annotation/label refers to. The pointer should be before the label. This means that the pointer will be drawn at the current position of the text box, and the text box will move to the right.

Therefore, the x-axis of the text box will be associated with the new box_x variable. This change must also be reflected in other variables using the textbox x-axis. Here is the updated code:

mkdir image_annotation
Copy after login
Copy after login
Copy after login

In the above code, the ImageDraw.circle() method (where 10 is the radius) is used to draw the pointer at the specified point. box_xThe variable is the new value of the x-axis of the text box.

Full code

The following is the complete code of the script.py file:

pip install virtualenv
Copy after login
Copy after login
Copy after login

Conclusion

Image processing is not always as difficult as it seems. Although some image processing libraries cannot directly solve your problem with their modules, you can use existing modules to implement a specific solution for your use case. That’s the beauty of coding – being able to solve problems with custom and specific solutions.

In this tutorial, you learned how to use Python’s Pillow library to annotate images, add word-wrapped multi-line text boxes, and more. You also learned how to write mathematical formulas that can help you with image processing.

Please refer to the Pillow documentation for details on the modules used.

The above is the detailed content of Wrap and Render Multiline Text on Images Using Python&#s Pillow Library. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1664
14
PHP Tutorial
1268
29
C# Tutorial
1242
24
Python vs. C  : Applications and Use Cases Compared Python vs. C : Applications and Use Cases Compared Apr 12, 2025 am 12:01 AM

Python is suitable for data science, web development and automation tasks, while C is suitable for system programming, game development and embedded systems. Python is known for its simplicity and powerful ecosystem, while C is known for its high performance and underlying control capabilities.

Python: Games, GUIs, and More Python: Games, GUIs, and More Apr 13, 2025 am 12:14 AM

Python excels in gaming and GUI development. 1) Game development uses Pygame, providing drawing, audio and other functions, which are suitable for creating 2D games. 2) GUI development can choose Tkinter or PyQt. Tkinter is simple and easy to use, PyQt has rich functions and is suitable for professional development.

The 2-Hour Python Plan: A Realistic Approach The 2-Hour Python Plan: A Realistic Approach Apr 11, 2025 am 12:04 AM

You can learn basic programming concepts and skills of Python within 2 hours. 1. Learn variables and data types, 2. Master control flow (conditional statements and loops), 3. Understand the definition and use of functions, 4. Quickly get started with Python programming through simple examples and code snippets.

Python vs. C  : Learning Curves and Ease of Use Python vs. C : Learning Curves and Ease of Use Apr 19, 2025 am 12:20 AM

Python is easier to learn and use, while C is more powerful but complex. 1. Python syntax is concise and suitable for beginners. Dynamic typing and automatic memory management make it easy to use, but may cause runtime errors. 2.C provides low-level control and advanced features, suitable for high-performance applications, but has a high learning threshold and requires manual memory and type safety management.

How Much Python Can You Learn in 2 Hours? How Much Python Can You Learn in 2 Hours? Apr 09, 2025 pm 04:33 PM

You can learn the basics of Python within two hours. 1. Learn variables and data types, 2. Master control structures such as if statements and loops, 3. Understand the definition and use of functions. These will help you start writing simple Python programs.

Python and Time: Making the Most of Your Study Time Python and Time: Making the Most of Your Study Time Apr 14, 2025 am 12:02 AM

To maximize the efficiency of learning Python in a limited time, you can use Python's datetime, time, and schedule modules. 1. The datetime module is used to record and plan learning time. 2. The time module helps to set study and rest time. 3. The schedule module automatically arranges weekly learning tasks.

Python: Automation, Scripting, and Task Management Python: Automation, Scripting, and Task Management Apr 16, 2025 am 12:14 AM

Python excels in automation, scripting, and task management. 1) Automation: File backup is realized through standard libraries such as os and shutil. 2) Script writing: Use the psutil library to monitor system resources. 3) Task management: Use the schedule library to schedule tasks. Python's ease of use and rich library support makes it the preferred tool in these areas.

Python: Exploring Its Primary Applications Python: Exploring Its Primary Applications Apr 10, 2025 am 09:41 AM

Python is widely used in the fields of web development, data science, machine learning, automation and scripting. 1) In web development, Django and Flask frameworks simplify the development process. 2) In the fields of data science and machine learning, NumPy, Pandas, Scikit-learn and TensorFlow libraries provide strong support. 3) In terms of automation and scripting, Python is suitable for tasks such as automated testing and system management.

See all articles