This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English version of the page.

Note: This page has been translated by MathWorks. Click here to see
To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

images.roi.Freehand class

Package: images.roi

Freehand region of interest

Description

The images.roi.Freehand class creates a freehand region-of-interest (ROI) object. You call the draw method of the object to begin drawing the ROI interactively by using your mouse.

To create a freehand ROI interactively, position the pointer on the axes and click and drag to draw the ROI shape. Release the pointer to close the shape. To delete a freehand ROI, position the pointer over the ROI, right-click, and select Delete Freehand from the context menu. For more information about interactive behaviors including keyboard shortcuts, see Tips.

The images.roi.Freehand class is a handle class.

Creation

Description

example

h = images.roi.Freehand creates an instance of the images.roi.Freehand class with default properties.

h = images.roi.Freehand(ax) creates the ROI in the axes specified by ax.

h = images.roi.Freehand(___,Name,Value) modifies the appearance and behavior of the ROI using one or more name-value pairs to specify properties. You can set properties using name-value pairs with or without specifying ax.

Input Arguments

expand all

Parent of the ROI, specified as an Axes object.

Properties

expand all

Public Properties

Close the freehand ROI, specified as a logical value true or false. If true (default), images.roi.Freehand closes the ROI by connecting the last point drawn to the first point drawn.

ROI color, specified as a MATLAB® ColorSpec (Color Specification).

Example: 'green'

Example: 'g'

Example: [0 1 0]

ROI can be interactively deleted via a context menu, specified as true or false. When the value is true (default), you can delete the ROI via the context menu. To disable this context menu item, set this property to false. When the value is set to false, you can still delete the ROI by calling the delete function specifying the handle to the ROI as the input.

Area of the axes in which you can interactively place the ROI, specified as one of the values in this table.

ValueDescription
'auto'The drawing area is the current axes limits (default).
'unlimited'The drawing area has no boundary and ROIs can be drawn or dragged to extend beyond the axes limits.
[x,y,w,h]The drawing area is restricted to a rectangular region beginning at (x,y), and extending to width w and height h.

Transparency of the ROI face, specified as a numeric scalar value in the range [0 1]. When the value is 1, the ROI face is fully opaque. When the value is 0, the ROI face is completely transparent.

ROI face can capture clicks, specified as true or false. When true (default), the ROI face captures mouse clicks. When false, the ROI face does not capture mouse clicks.

Visibility of the ROI handle in the Children property of the parent, specified as one of the values in this table.

ValueDescription
'on'The object handle is always visible (default).
'off'The object handle is hidden at all times.
'callback' The object handle is visible from within callbacks or functions invoked by callbacks, but not from within functions invoked from the command line.

Interactivity of the ROI, specified as one of the values in this table.

ValueDescription
'all'The ROI is fully interactable (default).
'none'The ROI is not interactable, and no drag points are visible.
'translate'The ROI can be translated (moved) within the drawing area but not reshaped. This value is not available for use with images.roi.Point objects.
'reshape'The ROI can be reshaped but not translated. This value is not available for use with images.roi.Point objects or images.roi.Rectangle objects.

ROI label, specified as a character vector or string. By default, the ROI has no label ('').

Width of the ROI edge, specified as a positive numeric scalar in points. The default value is three times the number of points per screen pixel.

Control the freehand drawing style during interactive placement, specified as the logical value true or false. When the value is false (the default), a single click and drag gesture completes the freehand ROI. When the value is true, multiple click and drag gestures can be combined with straight edges to make a more complex freehand ROI shape.

ROI parent, specified as an Axes object. A UIAxes cannot be the parent of the ROI.

Position of the ROI, specified as an n-by-2 numeric array of the form [x1 y1;...;xn yn], where n is the number of points. Each row specifies the position of a point defining the ROI.

Selection state of the ROI, specified as the logical value true or false. You can also set this property interactively. For example, clicking on the ROI selects the ROI and sets this property to true. Similarly, pressing the Ctrl key and clicking the ROI deselects the ROI and sets the value of this property to false.

Color of the ROI when selected, specified as a MATLAB ColorSpec (Color Specification). The intensities must be in the range [0,1]. If 'SelectedColor' is set to 'none', then the value of Color defines the color of the ROI for all states, selected or not.

Example: 'green'

Example: 'g'

Example: [0 1 0]

Smooth ROI during interactive placement, specified as a positive numeric scalar. Filter the x and y coordinates of the ROI after interactive placement with a Gaussian smoothing kernel with standard deviation specified by Smoothing. The filter size is 2*ceil(2*Smoothing) + 1.

Color of the ROI stripe, specified as a MATLAB ColorSpec (Color Specification) value. By default, the edge of an ROI is solid colored. If you specify StripeColor, the ROI edge is striped. The striping consists of a combination of the value specified by 'Color' and this value.

Example: 'green'

Example: 'g'

Example: [0 1 0]

Tag to associate with the ROI, specified as a character vector or string. Use the tag value to find the ROI object in a hierarchy of objects using the findobj function.

Context menu, specified as a ContextMenu object. Use this property to display a custom context menu when you right-click the ROI. You can create a custom context menu by using the uicontextmenu function and then configuring context menu properties.

Data to associate with the ROI, specified as any MATLAB data. For example, you can specify a scalar, vector, matrix, cell array, string, character array, table, or structure. MATLAB does not use this data.

ROI visibility, specified as one of the values in this table.

ValueDescription
'on'Display the ROI (default).
'off'Hide the ROI without deleting it. You still can access the properties of an invisible ROI.

Control points used to reshape ROI, specified as an n-by-1 array. In the array, a row with the value true indicates the position on the ROI edge is a waypoint. The length of the Waypoints array must match the number of rows in the Position property. Dragging a waypoint modifies the freehand-drawn region between the specified waypoint and its immediate neighboring waypoints. If empty (the default), images.roi.Freehand generates waypoints automatically at locations of increased curvature.

Methods

expand all

Events

Event NameTriggerEvent DataEvent Attributes
DeletingROIROI is about to be interactively deleted.event.EventData

NotifyAccess: private

ListenAccess: public

DrawingStartedROI is about to be interactively drawn.event.EventData

NotifyAccess: private

ListenAccess: public

DrawingFinishedROI has been interactively drawn.event.EventData

NotifyAccess: private

ListenAccess: public

MovingROIROI shape or location is being interactively changed.images.roi.ROIMovingEventData

NotifyAccess: private

ListenAccess: public

ROIMovedROI shape or location has been interactively changed.images.roi.ROIMovingEventData

NotifyAccess: private

ListenAccess: public

ROIClickedROI has been clicked.images.roi.ROIClickedEventData

NotifyAccess: private

ListenAccess: public

AddingWaypointA waypoint is about to be interactively added to the ROI.event.EventData

NotifyAccess: private

ListenAccess: public

WaypointAddedA waypoint has been interactively added to the ROI.event.EventData

NotifyAccess: private

ListenAccess: public

RemovingWaypointA waypoint is about to be interactively removed from the ROI.event.EventData

NotifyAccess: private

ListenAccess: public

WaypointRemovedA waypoint has been interactively removed from the ROI.event.EventData

NotifyAccess: private

ListenAccess: public

Examples

collapse all

Read an image into the workspace and display it.

I = imread('baby.jpg');
figure
imshow(I)

Create a freehand ROI on the image, using the Position property to specify the vertices of the ROI. For programmatically created ROIs, if you want the ROI drawn in a specific axes, you must specify that axes as an input argument. Otherwise, an instance of the images.roi.Freehand class is created but not displayed. In this example, specify the current axes (gca) to draw the ROI on the image in that axes.

h = images.roi.Freehand(gca,'Position',[100 150;200 250;300 350;150 450]);

Tips

  • The ROI supports the following interactivity, including keyboard shortcuts.

    BehaviorKeyboard shortcut
    Finish drawing (close) the ROI.

    Right-click.

    Position pointer over the first vertex and click.

    Press Enter.

    Stop drawing the ROI.Press Esc. The function returns a valid ROI object with an empty Position field.
    Add a new vertex (waypoint) to the ROI.

    Position the pointer on the edge of the ROI and double-click.

    Position the pointer on the edge of the ROI, right-click, choose Add Waypoint from the context menu.

    Remove a vertex (waypoint) from the ROI.

    Position the pointer on a vertex, right-click, choose Remove Waypoint from the context menu.

    Resize (reshape) the ROI.

    Position pointer over a vertex and then click and drag.

    Add a new vertex to the polygon and then click and drag.

    Move the ROI.Position the pointer on the ROI. The pointer changes to the fleur shape. Click and drag the ROI.
  • For information about using an ROI in an app created with App Designer, see Using ROIs in Apps Created with App Designer.

Introduced in R2018b