Annotate Image Displays and Draw ROIs

Overlay masks and labels on images, and draw regions of interest of many shapes

The toolbox supports a set of objects that you can use to create ROIs of many shapes, such circles, ellipses, polygons, rectangles, and hand-drawn shapes. After you create the objects, you can modify their shape, position, appearance, and behavior.

Functions

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Overlay Mask and Labels on Image

`imoverlay`	Burn binary mask into 2-D image
`labeloverlay`	Overlay label matrix regions on 2-D image
`uipaint`	Draw using paintbrush in viewer window (Since R2026a)

Viewer-Based ROIs

Draw ROI Shapes

uidraw Interactively draw ROI in viewer window (Since R2026a)

ROI Shapes

`Angle`	Angle annotation (Since R2026a)
`Circle`	Circle annotation (Since R2026a)
`Ellipse`	Ellipse annotation (Since R2026a)
`Freehand`	Freehand annotation (Since R2026a)
`Line`	Line annotation (Since R2024a)
`Point`	Point annotation (Since R2024a)
`Polygon`	Polygon annotation (Since R2026a)
`Polyline`	Polyline annotation (Since R2026a)
`Rectangle`	Rectangle annotation (Since R2026a)

Axes-Based ROIs

Draw ROI Shapes

`drawassisted`	Create customizable freehand ROI with assistance from object edges
`drawcircle`	Create customizable circular ROI
`drawcrosshair`	Create customizable crosshair ROI
`drawcuboid`	Create customizable cuboidal ROI
`drawellipse`	Create customizable elliptical ROI
`drawfreehand`	Create customizable freehand ROI
`drawline`	Create customizable linear ROI
`drawpoint`	Create customizable point ROI
`drawpolygon`	Create customizable polygonal ROI
`drawpolyline`	Create customizable polyline ROI
`drawrectangle`	Create customizable rectangular ROI

ROI Shapes

`AssistedFreehand`	Assisted freehand region of interest
`Circle`	Circular region of interest
`Crosshair`	Crosshair region of interest
`Cuboid`	Cuboidal region of interest
`Ellipse`	Elliptical region of interest
`Freehand`	Freehand region of interest
`Line`	Line region of interest
`Point`	Point region of interest
`Polygon`	Polygonal region of interest
`Polyline`	Polyline region of interest
`Rectangle`	Rectangular region of interest

Customize ROI Shapes

`draw`	Begin drawing ROI interactively
`reduce`	Reduce density of points in ROI
`beginDrawingFromPoint`	Begin drawing ROI from specified point
`inROI`	Query if points are located in ROI
`bringToFront`	Bring ROI to front of Axes stacking order
`wait`	Block MATLAB command line until ROI operation is finished

Topics

Specify ROIs

Create ROI Shapes
ROI objects represent ROIs as geometric and hand-drawn shapes.

Create Interactive ROIs Using Events and Callback Functions

Subsample or Simplify a Freehand ROI
This example shows how to subsample or reduce the number of points in a Freehand ROI object.
Create Freehand ROI Editing Tool
This example shows how to create a simple tool to edit the shape of a freehand ROI using another ROI object.
Use Wait Function After Drawing ROI
This example shows how to define a custom wait function that blocks the MATLAB® command line until you finish positioning a rectangle.
Create Image Comparison Tool Using ROIs
This example shows how to use the new ROI functions to create an interactive image comparison tool.

Featured Examples

Label Volume Display Using Point and Line Annotations

Add and edit point and line annotations in a Viewer object displaying a 3-D Brain MRI scan.

Open Live Script

Explore Blocked Image Details with Interactive ROIs

Display a detailed region of a blocked image selected interactively using ROI tools.

Open Live Script