affineOutputView

Create output view for warping images

Syntax

Rout = affineOutputView(sizeA,tform)

Rout = affineOutputView(sizeA,tform,BoundsStyle=style)

Description

Rout = affineOutputView(sizeA,tform) takes the size of an input image, sizeA, and an affine geometric transformation, tform, and returns a spatial referencing object, Rout. You can use this object as input to imwarp to control the output limits and grid spacing of a warped image.

Rout = affineOutputView(sizeA,tform,BoundsStyle=style) also specifies constraints on the spatial limits of the output view, such as whether the output view should completely contain the output image or whether the output view should match the input limits.

Examples

Warp Image Using Different Output View Styles

Read and display an image. To see the spatial extents of the image, make the axes visible.

A = imread("kobi.png");
A = imresize(A,0.25);
iptsetpref("ImshowAxesVisible","on")
imshow(A)

Create a 2-D affine transformation. This example creates a randomized transformation that consists of scale by a factor in the range [1.2, 2.4], rotation by an angle in the range [-45, 45] degrees, and horizontal translation by a distance in the range [100, 200] pixels.

tform = randomAffine2d("Scale",[1.2,2.4],"XTranslation",[100 200],"Rotation",[-45,45]);

Create three different output views for the image and transformation.

centerOutput = affineOutputView(size(A),tform,"BoundsStyle","CenterOutput");
followOutput = affineOutputView(size(A),tform,"BoundsStyle","FollowOutput");
sameAsInput = affineOutputView(size(A),tform,"BoundsStyle","SameAsInput");

Apply the transformation to the input image using each of the different output view styles.

BCenterOutput = imwarp(A,tform,"OutputView",centerOutput);
BFollowOutput = imwarp(A,tform,"OutputView",followOutput);
BSameAsInput = imwarp(A,tform,"OutputView",sameAsInput);

Display the resulting images.

imshow(BCenterOutput)
title("CenterOutput Bounds Style");

imshow(BFollowOutput)
title("FollowOutput Bounds Style");

imshow(BSameAsInput)
title("SameAsInput Bounds Style");

iptsetpref("ImshowAxesVisible","off")

Input Arguments

sizeA — Input image size

2-element numeric vector | 3-element numeric vector

Input image size, specified as a 2-element numeric vector for 2-D image input or a 3-element numeric vector for 3-D volumetric image input.

tform — Geometric transformation

geometric transformation object

Geometric transformation, specified as a geometric transformation object listed in the table.

Geometric Transformation Object	Description
2-D Geometric Transformations
transltform2d	Translation transformation
rigidtform2d	Rigid transformation: translation and rotation
simtform2d	Similarity transformation: translation, rotation, and isotropic scaling
affinetform2d	Affine transformation: translation, rotation, anisotropic scaling, reflection, and shearing
3-D Geometric Transformations
transltform3d	Translation transformation
rigidtform3d	Rigid transformation: translation and rotation
simtform3d	Similarity transformation: translation, rotation, and isotropic scaling
affinetform3d	Affine transformation: translation, rotation, anisotropic scaling, reflection, and shearing

Note

You can also specify tform as an affine2d object or an affine3d object. However, these objects are not recommended. For more information, see Version History.

style — Bounds style

"CenterOutput" (default) | "FollowOutput" | "SameAsInput"

Bounds style, specified as one of the following values.

Style	Description
"CenterOutput"	Center the view at the center of the image in output space while allowing translation to move the output image out of view.
"FollowOutput"	Set the limits of the output view to completely contain the output image.
"SameAsInput"	Set the output limits to be the same as the input limits.

Output Arguments

Rout — Spatial referencing

imref2d object | imref3d object

Spatial referencing, returned as an imref2d or imref3d object. Use Rout as the OutputView argument of the imwarp function to specify the spatial referencing of the warped output.

Extended Capabilities

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced in R2019b

R2022b: Supports new geometric transformation objects

Starting in R2022b, most Image Processing Toolbox™ functions create and perform geometric transformations using the premultiply convention. Accordingly, you can now specify tform as a geometric transformation object that uses the premultiply convention, such as an affinetform2d or affinetform3d object.

Although you can still specify tform as an affine2d or affine3d object, these objects are not recommended because they use the postmultiply convention. You can streamline your geometric transformation workflows by switching to objects that use the premultiply convention. For more information, see Migrate Geometric Transformations to Premultiply Convention.

R2021b: Support for thread-based environments

affineOutputView now supports thread-based environments.