---
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 {{< ilink "/docs/manual/advanced/annotation-with-polygons/creating-mask" "Creating masks" >}}.
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** subtracts 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. |
|  | **Hide mask**. When drawing or editing a mask, you can enable this feature to temporarily hide the mask, allowing you to see the objects underneath more clearly. |
|  | **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
To annotate with brush, do the following:
1. From the {{< ilink "/docs/manual/basics/CVAT-annotation-Interface/controls-sidebar" "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
{{< ilink "/docs/manual/basics/CVAT-annotation-Interface/objects-sidebar" "objects sidebar" >}}.
To add the next object, repeat steps 1 to 5.
All added objects will be visible on the image and the
{{< ilink "/docs/manual/basics/CVAT-annotation-Interface/objects-sidebar" "objects sidebar" >}}.
To save the job with all added objects, on the top menu, click **Save** .
## Annotation with polygon-to-mask
To annotate with polygon-to-mask, do the following:
1. From the {{< ilink "/docs/manual/basics/CVAT-annotation-Interface/controls-sidebar" "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 {{< ilink "/docs/manual/basics/CVAT-annotation-Interface/objects-sidebar" "objects sidebar" >}}.
To add the next object, repeat steps 1 to 5.
All added objects will be visible on the image and the
{{< ilink "/docs/manual/basics/CVAT-annotation-Interface/objects-sidebar" "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 {{< ilink "/docs/manual/advanced/ai-tools" "AI tool" >}} masks to polygons.
To do this, use the following {{< ilink "/docs/manual/advanced/ai-tools" "AI tool" >}} 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 {{< ilink "/docs/manual/advanced/import-datasets" "Export dataset" >}}
Import follows the general {{< ilink "/docs/manual/advanced/import-datasets" "import dataset" >}} procedure,
with the additional option of converting masks to polygons.
{{% alert title="Note" color="primary" %}}
This option is available for formats that work with masks only.
{{% /alert %}}
To use it, when uploading the dataset, switch the **Convert masks to polygon** toggle to the right:
