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createMask

Create binary mask image from ROI

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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.

example

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

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Open Live Script

Read image into the workspace and display it.

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

Figure contains an axes object. The hidden axes object contains an object of type image.

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');

Figure contains an axes object. The hidden axes object contains 2 objects of type image, images.roi.ellipse.

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)

Figure contains an axes object. The hidden axes object contains an object of type image.

Input Arguments

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

AssistedFreehandFreehandPolyline
CircleLineRectangle
EllipsePolygon 

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

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

Input image array, specified as a numeric array.

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

Output Arguments

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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

See Also

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