Registration Estimator
Register 2-D grayscale images
Description
The Registration Estimator app aligns 2-D grayscale images using automatic image registration. Using this app, you can:
Compare feature-based, intensity-based, and nonrigid registration techniques interactively.
Obtain the registered image and the geometric transformation.
Generate a function with the desired registration technique and settings. Call this function to register other images using the same settings.
More
Feature-Based Techniques
Feature-based registration techniques automatically detect distinct image features such as sharp corners, blobs, or regions of uniform intensity. The moving image undergoes a single global transformation to provide the best alignment of corresponding features with the fixed image.
FAST detects corner features, especially in scenes of human origin such as streets and indoor rooms. FAST supports single-scale images and point-tracking.
MinEigen also detects corner features. MinEigen supports single-scale images and point-tracking.
Harris also detects corner features, using a more efficient algorithm than MinEigen. Harris supports single-scale images and point-tracking.
BRISK also detects corner features. Unlike the preceding algorithms, BRISK supports changes in scale and rotation, and point-tracking.
ORB detects corners in images with changes in scale and/or rotation.
SURF detects blobs in images and supports changes in scale and rotation.
KAZE detects multiscale blob features from a scale space constructed using nonlinear diffusion.
MSER detects regions of uniform intensity. MSER supports changes in scale and rotation, and is more robust to affine transformations than the other feature-based algorithms.
Intensity-Based Techniques
Registration Estimator offers three registration techniques that use intensity metric optimization:
Monomodal intensity
Multimodal intensity
Phase correlation
Intensity-based registration techniques correlate image intensity in the spatial or frequency domain. The moving image undergoes a single global transformation to maximize the correlation of its intensity with the intensity of the fixed image.
Monomodal intensity registers images with similar brightness and contrast that are captured on the same type of scanner or sensor. For example, use monomodal intensity to register MRI scans taken of similar subjects using the same imaging sequence.
Multimodal intensity registers images with different brightness and contrast. These images can come from two different types of devices, such as two camera models or two types of medical imaging systems (such as CT and MRI). These images can also come from a single device. For example, use multimodal intensity to register images taken with the same camera using different exposure settings, or to register MRI images acquired during a single session using different imaging sequences.
Phase correlation registers images in the frequency domain. Like multimodal intensity, phase correlation is invariant to image brightness. Phase correlation is more robust to noise than the other intensity-based registration techniques.
Nonrigid Registration Techniques
Nonrigid registration applies nonglobal transformations to the
moving image. Nonrigid transformations generate a displacement field, in which each
pixel location in the fixed image is mapped to a corresponding location in the
moving image. The moving image is then warped according to the displacement field
and resampled using linear interpolation. For more information about estimating a
displacement field for nonrigid transformations, see imregdemons
.
Open the Registration Estimator App
MATLAB® Toolstrip: On the Apps tab, under Image Processing and Computer Vision, click the Registration Estimator app icon.
MATLAB command prompt: Enter
registrationEstimator
.
Programmatic Use
registrationEstimator
registrationEstimator
opens the Registration Estimator app,
which enables you to perform intensity-based, feature-based, and nonrigid image
registration.
registrationEstimator(moving
,fixed
)
moving
,fixed
)registrationEstimator(
opens Registration Estimator, loading the grayscale images
moving
,fixed
)moving
and fixed
into the app.
registrationEstimator close
registrationEstimator close
closes all open instances of the
Registration Estimator app.
Tips
You can register images and generate functions for all feature-based techniques without a Computer Vision Toolbox™ license. However, to run an autogenerated function that uses a feature-based registration technique, you must have Computer Vision Toolbox. For more information, see Export Results from Registration Estimator App.
Version History
Introduced in R2017aR2021a: Support for KAZE and ORB registration techniques
The app now supports two additional registration techniques: KAZE and ORB.
The KAZE technique is a multiscale 2-D feature detection and description algorithm in nonlinear scale spaces.
The ORB technique detects corners in images with changes in scale, rotations, or both.
MATLAB Command
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Run the command by entering it in the MATLAB Command Window. Web browsers do not support MATLAB commands.
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