---
title: 'Annotation with brush tool'
linkTitle: 'Annotation with brush tool'
weight: 13
description: 'Guide to annotating tasks using brush tools.'
---
With a brush tool, you can create masks for disjoint objects, that have multiple parts,
such as a house hiding behind trees, a car behind a pedestrian, or a pillar behind a
traffic sign.
The brush tool has several modes, for example: erase pixels, change brush shapes, and polygon-to-mask mode.
Use brush tool for Semantic (Panoptic) and Instance Image Segmentation tasks.
For more information about segmentation masks in CVAT, see [Creating masks](/docs/manual/advanced/annotation-with-polygons/creating-mask/).
See:
- [Brush tool menu](#brush-tool-menu)
- [Annotation with brush](#annotation-with-brush)
- [Annotation with polygon-to-mask](#annotation-with-polygon-to-mask)
- [Remove underlying pixels](#remove-underlying-pixels)
- [AI Tools](#ai-tools)
- [Import and export](#import-and-export)
## Brush tool menu
The brush tool menu appears on the top of the screen after you click **Shape**:
It has the following elements:
|Element|Description|
|----|-----|
|| **Save mask** saves the created mask. The saved mask will appear on the object sidebar|
|| **Save mask and continue** adds a new mask to the object sidebar and allows you to draw a new one immediately.|
|| **Brush** adds new mask/ new regions to the previously added mask).|
||**Eraser** removes part of the mask.|
||**Polygon** selection tool. Selection will become a mask.|
||**Remove polygon selection** substracts part of the polygon selection.|
||**Brush size** in pixels.
**Note:** Visible only when **Brush** or **Eraser** are selected.|
||**Brush shape** with two options: circle and square.
**Note:** Visible only when **Brush** or **Eraser** are selected.|
||**Remove underlying pixels**. When you are drawing or editing a mask with this tool,
pixels on other masks that are located at the same positions as the pixels of the
current mask are deleted.|
||**Label** that will be assigned to the newly created mask||
||**Move**. Click and hold to move the menu bar to the other place on the screen|
## Annotation with brush
Prerequisites: [Create task](/docs/manual/basics/creating_an_annotation_task/), upload the image, add labels,
and open the workspace.
Do the following:
1. From the [controls sidebar](/docs/manual/basics/controls-sidebar/), select **Brush** .
2. In the **Draw new mask** menu, select label for your mask, and click **Shape**.
The **Brush** tool will be selected by default.
3. With the brush, draw a mask on the object you want to label.
To erase selection, use **Eraser** 
4. After you applied the mask, on the top menu bar click **Save mask** 
to finish the process (or **N** on the keyboard).
5. Added object will appear on the [objects sidebar](/docs/manual/basics/objects-sidebar/).
To add the next object, repeat steps 1 to 5.
All added objects will be visible on the image and the [objects sidebar](/docs/manual/basics/objects-sidebar/).
To save the job with all added objects, on the top menu click **Save** .
## Annotation with polygon-to-mask
Prerequisites: [Create task](/docs/manual/basics/creating_an_annotation_task/), upload the image,
add labels, and open the workspace.
Do the following:
1. From the [controls sidebar](/docs/manual/basics/controls-sidebar/), select **Brush** .
2. In the **Draw new mask** menu, select label for your mask, and click **Shape**.
3. In the brush tool menu, select **Polygon** .
4. With the **Polygon** tool, draw a mask for the object you want to label.
To correct selection, use **Remove polygon selection** .
5. Use **Save mask**  (or **N** on the keyboard)
to switch between add/remove polygon tools:
6. After you added the polygon selection, on the top menu bar click **Save mask** 
to finish the process (or **N** on the keyboard).
7. Click **Save mask**  again (or **N** on the keyboard).
The added object will appear on the [objects sidebar](/docs/manual/basics/objects-sidebar/).
To add the next object, repeat steps 1 to 5.
All added objects will be visible on the image and the [objects sidebar](/docs/manual/basics/objects-sidebar/).
To save the job with all added objects, on the top menu click **Save** .
## Remove underlying pixels
Use **Remove underlying pixels** tool when you want to add a mask and simultaneously delete the pixels of
other masks that are located at the same positions. It is a highly useful feature to avoid meticulous drawing edges twice between two different objects.
## AI Tools
You can convert [AI tool](/docs/manual/advanced/ai-tools/) masks to polygons.
To do this, use the following [AI tool](/docs/manual/advanced/ai-tools/) menu:
1. Go to the **Detectors** tab.
2. Switch toggle **Masks to polygons** to the right.
3. Add source and destination labels from the drop-down lists.
4. Click **Annotate**.
## Import and export
For export, see [Export dataset](/docs/manual/advanced/export-import-datasets/)
Import follows the general [import dataset](/docs/manual/advanced/export-import-datasets/) procedure,
with the additional option of converting masks to polygons.
>**Note:** This option is available for formats that work with masks only.
To use it, when uploading the dataset, switch the **Convert masks to polygon** toggle to the right:
