47,766 research outputs found
Automatic image registration using evolutionary algorithm
Image registration is a process to obtain the spatial transformation of an input image to a reference image by which similarity measure is optimized between the two images. Mutual information is a similarity measure based on information theory used in the process of image registration. Mutual information compares the statistical dependency between images. Registration based on mutual information is robust and could use for a large class of mono modality and multimodality images. In this work we use mutual information as the similarity measure .There is a requirement to finding the global maxima of similarity measure, for this we use two algorithm simple genetic algorithm and share genetic algorithm and compare the result of these algorithm. In these optimization technique require several decision to made during implementation, such as encoding, selection method and evolution operator. In this work we use two selection method roulette-wheel method and tournament selection method. Result indicates that these optimization techniques can be used for efficient image registratio
Image Registration Using Redundant Wavelet Transforms
Imagery is collected much faster and in significantly greater quantities today compared to a few years ago. Accurate registration of this imagery is vital for comparing the similarities and differences between multiple images. Since human analysis is tedious and error prone for large data sets, we require an automatic, efficient, robust, and accurate method to register images. Wavelet transforms have proven useful for a variety of signal and image processing tasks, including image registration. In our research, we present a fundamentally new wavelet-based registration algorithm utilizing redundant transforms and a masking process to suppress the adverse effects of noise and improve processing efficiency. The shift-invariant wavelet transform is applied in translation estimation and a new rotation-invariant polar wavelet transform is effectively utilized in rotation estimation. We demonstrate the robustness of these redundant wavelet transforms for the registration of two images (i.e., translating or rotating an input image to a reference image), but extensions to larger data sets are certainly feasible. We compare the registration accuracy of our redundant wavelet transforms to the \u27critically sampled\u27 discrete wavelet transform using the Daubechies (7,9) wavelet to illustrate the power of our algorithm in the presence of significant additive white Gaussian noise and strongly translated or rotated images
An Orthogonal Learning Differential Evolution Algorithm for Remote Sensing Image Registration
We introduce an area-based method for remote sensing image registration. We use orthogonal learning differential evolution algorithm to optimize the similarity metric between the reference image and the target image. Many local and global methods have been used to achieve the optimal similarity metric in the last few years. Because remote sensing images are usually influenced by large distortions and high noise, local methods will fail in some cases. For this reason, global methods are often required. The orthogonal learning (OL) strategy is efficient when searching in complex problem spaces. In addition, it can discover more useful information via orthogonal experimental design (OED). Differential evolution (DE) is a heuristic algorithm. It has shown to be efficient in solving the remote sensing image registration problem. So orthogonal learning differential evolution algorithm (OLDE) is efficient for many optimization problems. The OLDE method uses the OL strategy to guide the DE algorithm to discover more useful information. Experiments show that the OLDE method is more robust and efficient for registering remote sensing images
Image registration using finite dimensional lie groups : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Mathematics at Massey University, Palmerston North, New Zealand
D'Arcy Thompson was a biologist and mathematician who, in his 1917 book `On
Growth and Form', posited a `Theory of Transformations', which is based on the observation
that a smooth, global transformation of space may be applied to the shape
of an organism so that its transformed shape corresponds closely to that of a related
organism. Image registration is the computational task of finding such transformations
between pairs of images.
In modern applications in areas such as medical imaging, the transformations are often
chosen from the infinite-dimensional diffieomorphism group. However, this differs from
Thompson's approach where the groups are chosen to be as simple as possible, and
are generally finite-dimensional. The main exception to this is the similarity group
of translation, rotation, and scaling, which is used to pre-align images. In this thesis
the set of planar Lie groups are investigated and applied to image registration of the
types of images that Thompson considered. As these groups are smaller, successful
registration in these groups provides more specifc information about the relationship
between the images than diffeomorphic registration does, as well as providing faster
implementations. We build a lattice of the Lie groups showing which are subgroups of
each other, and the groups are used to perform image registration by minimizing the
L2-norm of the difference between the group-transformed source image and the target
image. A robust, practical, and efficient algorithm for registration in Lie groups is
developed and tested on a variety of image types.
Each successful registration returns a point in a Lie group. Given several related images
(such as the hooves of several animals) it is possible to find smooth curves that pass
through the Lie group elements used to relate the various images. These curves can
then be employed to interpolate points between the set of images or to extrapolate to
new images that have not been seen before. We discuss the mathematics behind this
and demonstrate it on the images that Thompson used, as well as other datasets of
interest.
Finally, we consider using a sequence of the planar Lie groups to perform registration,
with the output from one group being used as the input to the next. We call this multiregistration,
and have identified two types: where the smallest group is a subgroup
of the next smallest, and so on up a chain, and where the groups are not directly
related, i.e., separated on the lattice. We demonstrate experimentally that multiregistration
can provide more information about the relationship between images than
simple registration. In addition, we show that transformations that cannot be obtained
by a single registration in any of the groups considered can be successfully reached
New Techniques for High-Contrast Imaging with ADI: the ACORNS-ADI SEEDS Data Reduction Pipeline
We describe Algorithms for Calibration, Optimized Registration, and Nulling
the Star in Angular Differential Imaging (ACORNS-ADI), a new, parallelized
software package to reduce high-contrast imaging data, and its application to
data from the SEEDS survey. We implement several new algorithms, including a
method to register saturated images, a trimmed mean for combining an image
sequence that reduces noise by up to ~20%, and a robust and computationally
fast method to compute the sensitivity of a high-contrast observation
everywhere on the field-of-view without introducing artificial sources. We also
include a description of image processing steps to remove electronic artifacts
specific to Hawaii2-RG detectors like the one used for SEEDS, and a detailed
analysis of the Locally Optimized Combination of Images (LOCI) algorithm
commonly used to reduce high-contrast imaging data. ACORNS-ADI is written in
python. It is efficient and open-source, and includes several optional features
which may improve performance on data from other instruments. ACORNS-ADI
requires minimal modification to reduce data from instruments other than
HiCIAO. It is freely available for download at
www.github.com/t-brandt/acorns-adi under a BSD license.Comment: 15 pages, 9 figures, accepted to ApJ. Replaced with accepted version;
mostly minor changes. Software update
Surgical planning tool for robotically assisted hearing aid implantation
PURPOSE : For the facilitation of minimally invasive robotically performed direct cochlea access (DCA) procedure, a surgical planning tool which enables the surgeon to define landmarks for patient-to-image registration, identify the necessary anatomical structures and define a safe DCA trajectory using patient image data (typically computed tomography (CT) or cone beam CT) is required. To this end, a dedicated end-to-end software planning system for the planning of DCA procedures that addresses current deficiencies has been developed. METHODS : Efficient and robust anatomical segmentation is achieved through the implementation of semiautomatic algorithms; high-accuracy patient-to-image registration is achieved via an automated model-based fiducial detection algorithm and functionality for the interactive definition of a safe drilling trajectory based on case-specific drill positioning uncertainty calculations was developed. RESULTS : The accuracy and safety of the presented software tool were validated during the conduction of eight DCA procedures performed on cadaver heads. The plan for each ear was completed in less than 20 min, and no damage to vital structures occurred during the procedures. The integrated fiducial detection functionality enabled final positioning accuracies of [Formula: see text] mm. CONCLUSIONS : Results of this study demonstrated that the proposed software system could aid in the safe planning of a DCA tunnel within an acceptable time
Locally Non-rigid Registration for Mobile HDR Photography
Image registration for stack-based HDR photography is challenging. If not
properly accounted for, camera motion and scene changes result in artifacts in
the composite image. Unfortunately, existing methods to address this problem
are either accurate, but too slow for mobile devices, or fast, but prone to
failing. We propose a method that fills this void: our approach is extremely
fast---under 700ms on a commercial tablet for a pair of 5MP images---and
prevents the artifacts that arise from insufficient registration quality
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