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Polar transform is a geometric transform, that transforms points form cartesian coordinates to so-called polar coordinates. In case of 2D space, a point in polar coordinate system is addressed by radius and angle. In image processing, polar transform is [...]
Affine Transformation for Landmark Based Registration Initializer in ITK
Published in The MIDAS Journal
Published in The MIDAS Journal
This document describes an affine transformation algorithm as an additional feature for landmark based registration in ITK www.itk.org. The algorithm is based on the paper by Spath, H [1]. The author derives a set of linear equations from paired landmarks and [...]
This paper describes the implementation of the LDFFD and TDFFD algorithms. Both quantify motion and deformation from an input image sequence by taking profit of the temporal dimension of velocity fields in the diffeomorphic registration framework to process [...]
This document presents a GUI application to manually select corresponding points in two data sets. The data sets can each be either an image or a point cloud. If both data sets are images, the functionality is equivalent to Matlab's 'cpselect' function. There [...]
In this paper, we describe a set of filters, implemented in the Insight Toolkit www.itk.org, for converting an image from Cartesian co-ordinate space to Polar co-ordinate space and vice-versa. Cartesian to Polar conversion of an image is a useful operation in [...]
This document describes a new class that takes an doxygen{Transform} and
evaluates the deformation at points in a user-defined region.
The class is implemented using the Insight Toolkit url{www.itk.org}.
This paper is accompanied with the source code, [...]
This paper describes the ITK implementation of a transform initializer to produce a rigid 3-D transform able to center a given point on an arbitrary plane. The resultant transform allows the user to "look at" a point from a given direction. The resultant [...]
Nonrigid image registration is an important, but resource demanding and time-consuming task in medical image analysis. This limits its application in time-critical clinical routines. In this report we explore acceleration of two time-consuming parts of a [...]
Kernel-based transforms such as the thin plate spline are frequently used to model deformations in medical
imaging. The existing implementation in ITK is capable of being used to warp images, but does not
work in the registration framework. The existing [...]
The recent ITKv4 refactoring includes several enhancements to the existing registration framework. These additional transform classes provide access to mappings described by dense displacement fields and their corresponding optimization which complement the [...]
An ITK Implementation of a Diffusion Tensor Images Resampling Filter
Published in The Insight Journal
Published in The Insight Journal
This paper describes the implementation of a resampling filter for Diffusion Tensor Images (DTI) in the Insight ToolKit (ITK). ITK already contains a filter for resampling scalar and vector images as well as several transformation and interpolation classes. [...]
Morphological erosion and dilation filters employ a structuring function, with flat structuring functions being the most common example. This article will use the term ``parabolic'', but much of the literature uses ``quadratic'' structuring functions are less [...]
In this article, we present an implementation of a flexible framework for non-parametric variational image registration, realized as part of ITK's finite difference solver hierarchy.
In a variational registration setting, the transformation is found by [...]
This document describes a module that extends the Insight Toolkit, ITK, which reads DICOM Spatial Rogistration Object files in itk::Transform's. Currently, DICOM files are read by applying the DCMTK library as a backend. An itk::DCMTKTransformIO class can be [...]
Transitively Consistent and Unbiased Multi-Image Registration using Numerically Stable Transformation Synchronisation
Published in The MIDAS Journal
Published in The MIDAS Journal
Transitive consistency of pairwise transformations is a desirable property of groupwise image registration procedures. The transformation synchronisation method (Bernard et al., 2015) is able to retrieve transitively consistent pairwise transformations from [...]
It is sometimes useful to be able to apply binary morphological operations, such as erosions and dilations, to labelled images in a fashion that preserves the labels. This article introduces a specialised class implementing parallel methods described in beare [...]
This document describes the implementation in ITK of the "point in circle" geometrical predicate.
Based on Jonathan Shewchuk's work which implements an exact version of the predicate using standard
floating point types and arithmetic, the implementation [...]
N-Dimensional Computation of Strain Tensor Images in the Insight Toolkit
Published in The Insight Journal
Published in The Insight Journal
Strain quantifies local deformation of a solid body. In medical imaging, strain reflects how tissue deforms
under load. Or, it can quantify growth or atrophy of tissue, such as the growth of a tumor. Additionally,
strain from the transformation that results [...]
Being able to quickly compute the inverse of a deformation field is often useful in the context of medical image analysis. While ITK supports this functionality, the current algorithms are slow and do not always yield accurate results. In this paper we [...]
This document describes the workflow for unwarping structural MR images, in particular T1-weighted SPGR and MP-RAGE scans, using reference scans of the Magphan(R) EMR051 Quantitative Imaging Phantom (a.k.a. ADNI Phantom) and the tools of the Computational [...]
An ITK Implementation of the Symmetric Log-Domain Diffeomorphic Demons Algorithm
Published in The Insight Journal
Published in The Insight Journal
This article provides an implementation of the symmetric log-domain diffeomorphic image registration algorithm, or symmetric demons algorithm for short. It generalizes Thirion's demons and the diffeomorphic demons algorithm. The main practical advantages of [...]
We present an open-source ITK implementation of a direct Fourier method for tomographic reconstruction, applicable to parallel-beam x-ray images. Direct Fourier reconstruction makes use of the central-slice theorem to build a polar 2D Fourier space from the [...]
Phase Correlation Method (PCM or SPOMF - Symmetric Phase-Only Matched Filter) is a well known image registration method, that exploits Fourier Shift Theorem property of Fourier Transform. Even though it is limited to estimate only shifts between two images, [...]
BinShrink: A multi-resolution filter with cache efficient averaging.
Published in The Insight Journal
Published in The Insight Journal
We present a new filter for the Insight Toolkit (ITK) for reducing the resolution of an image by an integer factor while averaging called BinShrink. This filter provides a new level of performance to ITK for reducing resolution and noise present in an image. [...]
In this work,
we extend a previously demonstrated entropy based groupwise registration method
to include a non-rigid deformation model based on B-splines.
We describe an open source implementation of the groupwise registration algorithm
using the [...]
Facet Analyser: ParaView plugin for automated facet detection and measurement of interplanar angles of tomographic objects
Published in The MIDAS Journal
Published in The MIDAS Journal
The presented ParaView plugin allows easy access to the algorithm described in Ref 1. It enables analysis of faceted objects that exhibit distortions in their digital representation, e.g. due to tomographic reconstruction artifacts.
The contributed [...]
An Open Source, Fast Ultrasound B-Mode Implementation for Commodity Hardware
Published in The Insight Journal
Published in The Insight Journal
This document describes an open source, high performance ultrasound B-Mode implementation based on the Insight Toolkit (ITK). ITK extensions are presented to calculate the radio-frequency (RF) signal envelope. A variety of 1D Fast Fourier Transform options [...]
