invert

Invert geometric transformation

Syntax

tformInv = invert(tform)

Description

tformInv = invert(tform) returns the inverse of the geometric transformation tform.

Examples

Invert 2-D Rotation

Read and display an image.

I = imread("pout.tif");
imshow(I)

Create a rigidtform2d object that defines a 30 degree clockwise rotation around the origin.

translation = [0 0];
theta = 30;
tform = rigidtform2d(theta,translation);

Apply the forward geometric transformation, tform, to the image. Display the rotated image.

J = imwarp(I,tform);
imshow(J)

Invert the geometric transformation. The result is a new rigidtform2d object that represents a 30 degree rotation in the counterclockwise direction.

invtform = invert(tform);

Apply the inverse geometric transformation, invtform, to the rotated image J. The final image, K, has the same size, shape, and orientation as the original image. Black padding around the image results from the two transformations.

K = imwarp(J,invtform);
imshow(K)

Input Arguments

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
projtform2d	Projective transformation
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 object of type rigid2d, rigid3d, affine2d, affine3d, or projective2d. However, these objects are not recommended. For more information, see Version History.

Output Arguments

tformInv — Inverse geometric transformation

geometric transformation object

Inverse geometric transformation, returned as a geometric transformation object of the same type as tform.

Version History

Introduced in R2013a

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 object.

Although invert still supports objects that use the postmultiply convention, such as affine2d object, these objects are not recommended. You can streamline your geometric transformation workflows by switching to the new premultiply geometric transformation objects. For more information, see Migrate Geometric Transformations to Premultiply Convention.