createMask

Create binary mask image from ROI

Since R2018b

Syntax

bw = createMask(ROI)

bw = createMask(ROI,m,n)

bw = createMask(ROI,I)

bw = createMask(ROI,hImage)

Description

bw = createMask(ROI) returns a binary mask image with pixels inside the ROI set to true and pixels outside the ROI set to false.

bw = createMask(ROI,m,n) returns a binary mask image that is size [m,n].

bw = createMask(ROI,I) returns a binary mask image that is the size of the image I.

bw = createMask(ROI,hImage) returns a binary mask image that is the size of the Image object hImage.

Examples

Create Mask From Ellipse ROI

Read image into the workspace and display it.

I = imread('pears.png');
imshow(I)

Draw an elliptical ROI on the image, using the Center parameter to specify the location of the ellipse and theSemiAxes parameter to specify the shape of the ellipse. The example also specifies that the edge of the ellipse is a striped line.

h = drawellipse('Center',[447 204],'SemiAxes',[78 72], ...
    'RotationAngle',287,'StripeColor','m');

Get a binary mask from the ROI. Pixels inside the ROI are true and pixels outside the ROI are false. Display the mask.

mask = createMask(h);
imshow(mask)

Input Arguments

ROI — Region of interest

ROI object

Region of interest, specified as an ROI object of one of the following types:

AssistedFreehand	Freehand	Polyline
Circle	Line	Rectangle
Ellipse	Polygon

m — Row dimension of mask image

positive integer

Row dimension of the mask image, specified as a positive integer.

n — Column dimension of mask image

positive integer

Column dimension of the mask image, specified as a positive integer.

I — Input image array

numeric array

Input image array, specified as a numeric array.

hImage — Input image object

Image object

Input image object, specified as an Image object. For more details, see Image Properties.

Output Arguments

bw — Binary mask image

logical array

Binary mask image, returned as a logical array.

Data Types: logical

Tips

• For more information about classifying pixels on the ROI boundary, see Classify Pixels That Are Partially Enclosed by ROI.

• If you specify a mask size that does not match the size of the image associated with the ROI object, then createMask crops or zero-pads the mask to the specified size. The image associated with the ROI object is ROI.Parent.Children(2,1).CData.

Version History

Introduced in R2018b