cvat/site/content/en/docs/manual/advanced/annotation-with-brush-tool.md

title	linkTitle	weight	description
Annotation with brush tool	Annotation with brush tool	13	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
• Annotation with brush
• Annotation with polygon-to-mask
• Remove underlying pixels
• AI Tools
• 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: