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Brush Annotation Tool: your must-have for Object Segmentation

Lisa Uspenyeva

Learn how to annotate objects of any complexity by creating freeform outlines using the Brush annotation tool.

Brush Annotation Tool: your must-have for Object Segmentation

What is Brush Annotation Tool?

The Brush tool is one of the most important basic tools for image segmentation. It is specifically designed for creation of free-form and independent segmentation masks. With flexible customisable parameters such as size scaling, this tool is perfect for segmentation tasks of any complexity.

Brush is suitable for a variety of scenarios, from outlining objects with atypical shapes, such as rot on a tree leaf, to simpler tasks such as selecting circular objects such as road signs.

Also worth noting is the benefit of collaboration with other tools, such as Pen tool. Each tool is able to complement the functionality of the other, maximising the simplicity and accuracy of the segmentation process.

Using the Brush tool to segment objects such as road signs, tyre replacements, rotten fruit and manufacturing detailUsing the Brush tool to segment objects such as road signs, tyre replacements, rotten fruit and manufacturing detail

Brush tool is most effective when working with objects or areas that don't have clear geometric shapes, such as straight lines and sharp corners. It may be your must-have for object segmentation in many domains:

  • Automotive: The Brush Tool is an essential for highlighting and segmenting cars damage, including dents and chips. It can also highlight areas of tyre wear, providing a more accurate assessment of the condition of vehicle equipment.

  • Agriculture: Brush tool is used to segment areas on the surface of fruit and vegetables that are susceptible to disease, rot or mechanical damage. It also provides the ability to annotate pests, significantly improving the quality assessment of fruit and vegetables.

  • In the Medical field, The Brush tool is used to segment the contours of tumours on images or X-rays, and to highlight anomalies, defects and structures in organs such as blood vessels or nerves. This significantly increases the accuracy of diagnosis and treatment planning in medical practice.

  • In Infrastructure Inspection the Brush toll can be used to detect damage and hazards on roads, such as potholes or obstructions. This is particularly important for the safety of autonomous vehicles, which can use this information to safely avoid dangerous areas.

  • Construction: Brush can segment defects, holes, cracks and other damage to building materials, including concrete, brick and metal. This facilitates the inspection and planning process for construction work.

Video Tutorial for Brush in the New Labeling Toolbox

Learn to use our Brush Tool effectively in just a 5-minute video tutorial with clear instructions from our Supervisely expert. Get hands-on with the new interface and discover the features in our labeling toolbox.

Brush tool: key features

You can try out the tool's newest features for free directly on the Supervisely Platform.

One-click segmentation

The convenient scaling of this tool allows you to segment many simple round objects with literally one click. To change the brush diameter, simply use the toolbar menu or hotkeys [ ]. See how this feature makes annotation faster.

Segmentation of a pneumatic manometer control system with the Brush tool

Fast editing combining Brush, Eraser & Pen

You can edit the created mask by removing unnecessary parts or adding new parts using either the Brush, Eraser and Pen tool.

To add a part of the object, select the shape and draw the missing part. To delete a part of the object, press and hold the SHIFT key while repeating the previous steps. The algorithm is the same for both tools.

Modify the segmentation of pipeline valve which is using control production process with Brush and Pen tools

Bucket fill

No need to manually paint over unsegmented areas. Simply use the Bucket Fill tool to quickly fill holes in the segmentation with a single click. The selected object is highlighted with a grid of dots.

Filling holes in the segmentation of rolls of steel sheet using Brush tool

Polygon split mode

If you want to split the mask into two objects, you can use the Polygon Split instrument. Simply start outlining the desired area and finish the contour on its starting point. The shape you've just annotated will then emerge as a new object of the same class in the list of objects.

For a swift change in the class of an object, right-click on the selected item and choose the desired option from the pop-up list. In addition to class changes, this menu provides easy options for deleting or hiding an object.

Polygon split mode of Brush tool in agriculture: segmentation of rotten part of an apple

Segmenting Object presented by separate parts

One of the main features of the Brush tool is that it lets you select scattered separate parts of an object in the image, even if they're not connected. Just draw separate segments of the object using Brush tool - all of them will be on a single object mask. Press the SPACE key to finish the annotation and create the new object.

Using the Brush tool to segment a diseased leaf

Visualization Settings

Tailor your settings to suit your needs by adjusting opacity levels, selecting random colors for objects while annotating and and many other useful features.

Illustration showcasing various settings using a city scene as the backdrop


Control the Brush tool 8 more efficiently with HOTKEYS.

Draw pixel mask - CLICK + DRAW
Decrease brush size - [
Increase brush size - ]
Finish & start new - SPACE
Use Polygon Split (to cut mask into two objects) and Bucket Fill (to fill holes) in the tool subpanel
Finish area using SPACE or CLICK the first point.
Scene Navigation
Zoom with MOUSE WHEEL. Hold RIGHT MOUSE BUTTON to move scene.


In this post, we have examined the key features of the Brush tool currently accessible in Supervisely. We've explored its extensive capabilities and practical significance. With its flexible scalability and ease of use, the Brush tool becomes an integral part of your workflow, allowing you to quickly and accurately select and annotate objects of any shape.

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Lisa Uspenyeva
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Training data expert

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