A Jupyter widget for annotating images with bounding boxes

Usage no npm install needed!

<script type="module">
  import jupyterBboxWidget from 'https://cdn.skypack.dev/jupyter-bbox-widget';




A Jupyter widget for annotating images with bounding boxes. See a live demo on Binder.

from jupyter_bbox_widget import BBoxWidget
widget = BBoxWidget(
    classes=['apple', 'orange', 'pear'],

UI example

Create, edit, move, resize and delete bounding box annotations using the mouse.

Use widget.bboxes to get current annotations values:

# [{'x': 377, 'y': 177, 'width': 181, 'height': 201, 'label': 'apple'},
#  {'x': 219, 'y': 142, 'width': 169, 'height': 171, 'label': 'orange'},
#  {'x': 43,  'y': 174, 'width': 234, 'height': 195, 'label': 'pear'}]

You can also assign to widget.bboxes to display any annotations. For example, use the output of an object detection model to do model-assisted labeling.

widget.bboxes = [
    {'x': 377, 'y': 177, 'width': 181, 'height': 201, 'label': 'apple'},
    {'x': 219, 'y': 142, 'width': 169, 'height': 171, 'label': 'orange'},
    {'x': 43,  'y': 174, 'width': 234, 'height': 195, 'label': 'pear'}

Fruit photo by Umanoide on Unsplash


You can install using pip:

pip install jupyter_bbox_widget

If you are using Jupyter Notebook 5.2 or earlier, you may also need to enable the nbextension:

jupyter nbextension enable --py [--sys-prefix|--user|--system] jupyter_bbox_widget


Create and edit annotations with the mouse

  • click and drag to create a bbox
  • click and drag corners or edges to resize a bbox
  • click and drag inside a bbox to move it
  • in order to change a label select a new label below the image and click on label text

Keyboard shortcuts

When you click inside the widget area it will gain focus and start receiving keyboard events. An outline usually indicates that the element is focused. Normal Jupyter keyboard shortcuts won't work in this state. To unfocus the widget area click outside it or press Esc.

Some shortcuts act on the selected bbox. New bboxes are selected automatically when created. You can also select a bbox by clicking on it. Selected bbox is displayed on top of others and with a thicker border.

  • Digit keys 1-9 and 0 select a class label.
  • Esc unfocuses the widget
  • Enter is the same as pressing Submit button
  • Space is the same as pressing Skip button
  • Tab / Shift-Tab select next/previous bbox.
  • Keys acting on the selected bbox (assuming a QWERTY keyboard, other layouts should use any keys in the same locations):
    • W move up
    • A move left
    • S move down
    • D move right
    • Q shrink width
    • E grow width
    • R grow height
    • F shrink height
    • C assign selected class label
    • Holding Shift while pressing movement keys will increase step size

Skip and Submit events

You can define functions that will be called automatically when you press Skip or Submit buttons. This is useful for creating a workflow for annotating multiple images.

def skip():
    # move on to the next image
def save():
    # do stuff to save current annotations


There is an example of a simple annotation workflow in examples/introduction.ipynb notebook.

View only mode

You can disable editing of annotations by setting widget.view_only = True. This is useful for viewing annotation outputs without accidentally changing them.

Recording additional data

Sometimes you need to record more info about an object than just a location and a class label. For example, you might want to specify whether the object is in focus or blurred, record its size or other properties.

Let's say we want to apply a rating on a scale from 1 to 5 to every object in the image. We create a slider widget to edit the rating values:

w_rating = widgets.IntSlider(value=3, min=1, max=5, description='Rating')

And we attach it to the bbox widget.

widget.attach(w_rating, name='rating')

As a result all bboxes created afterwards will have a rating property and the w_rating widget can be used to display and manipulate the rating of the currently selected bbox.

Any number and any kind of ipywidgets widgets may be used in this way for creating richer annotations - number inputs, text inputs, checkboxes and so on (see widget list).

The notebook in examples/introduction.ipynb has an example and a more detailed explanation of this feature.

Development Installation

This project was inspired by a blogpost Creating Reactive Jupyter Widgets With Svelte and was created based on widget-svelte-cookiecutter template.

# First install the python package. This will also build the JS packages.
pip install -e .

When developing your extensions, you need to manually enable your extensions with the notebook / lab frontend. For lab, this is done by the command:

jupyter labextension install @jupyter-widgets/jupyterlab-manager --no-build
jupyter labextension install .

For classic notebook, you can run:

jupyter nbextension install --sys-prefix --symlink --overwrite --py jupyter_bbox_widget
jupyter nbextension enable --sys-prefix --py jupyter_bbox_widget

Note that the --symlink flag doesn't work on Windows, so you will here have to run the install command every time that you rebuild your extension. For certain installations you might also need another flag instead of --sys-prefix, but we won't cover the meaning of those flags here.

How to see your changes


To continuously monitor the project for changes and automatically trigger a rebuild, start Jupyter in watch mode:

jupyter lab --watch

And in a separate session, begin watching the source directory for changes:

npm run watch

After a change wait for the build to finish and then refresh your browser and the changes should take effect.


If you make a change to the python code then you will need to restart the notebook kernel to have it take effect.