LabelImg: The Ultimate Tool for Efficient Data Annotation

Abhishri Medewar
2 min readApr 7, 2023

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If you’re in the field of machine learning, you know the importance of labeled data. But if you’re new to the game, you may be wondering what data annotation is all about.

What is Data Annotation?

Example of Data Annotation

Data annotation is the process of adding metadata to your data, such as images, audio or text, to make it easier for machine learning algorithms to understand. This is typically done by manually labeling data with descriptive tags, annotations or bounding boxes.

Why is Data Annotation Required?

Data annotation is essential for supervised machine learning projects. Without accurate and consistent labeling, models cannot learn and make predictions. It can be a tedious and time-consuming task, but luckily there are tools like LabelImg to help.

What is LabelImg?

LabelImg is a free and open-source graphical image annotation tool that enables you to annotate object bounding boxes in images. LabelImg supports various annotation formats, including PascalVOC and YOLO, and can export annotations in XML, CSV, and TXT formats.

How to Install LabelImg on Linux/Windows?

The good news is that LabelImg is compatible with both Linux and Windows. To install on Linux, open your terminal and type:

sudo apt-get install pyqt5-dev-tools
git clone https://github.com/tzutalin/labelImg.git
cd labelImg
make qt5py3
pip install pyqt5==5.14.1
pip install lxml==4.9.1
python labelImg.py

To install on Windows, open your terminal and type(make sure you have python 3.x installed):

git clone https://github.com/tzutalin/labelImg.git
pip install PyQt5
pip install lxml
pyrcc5 -o libs/resources.py resources.qrc
python labelImg.py

Alternatively, you can opt for the standalone application that is accessible through the “release” section of the LabelImg Github page.

Shortcuts in LabelImg

LabelImg has a variety of keyboard shortcuts that can help speed up your annotation process. Some of the most useful include:

  • W: Create a bounding box
  • D: Move to the next image
  • A: Move to the previous image
  • Ctrl + d: Copy the current label and rect box
  • Delete: Delete the selected bounding box

With these shortcuts, you can save yourself a lot of time and focus on the fun part of machine learning — building great models.

In conclusion, LabelImg is an essential tool for anyone working with machine learning projects that require data annotation. By accurately labeling your data, you can create models that are capable of making accurate predictions. So what are you waiting for? Get labeling!

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