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/*========================================================================= |
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Program: Insight Segmentation & Registration Toolkit |
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Module: $RCSfile: itkNeighborhoodIterator.h.html,v $ |
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Language: C++ |
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Date: $Date: 2006/01/17 19:15:42 $ |
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Version: $Revision: 1.4 $ |
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Copyright (c) Insight Software Consortium. All rights reserved. |
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See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. |
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This software is distributed WITHOUT ANY WARRANTY; without even |
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
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PURPOSE. See the above copyright notices for more information. |
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=========================================================================*/ |
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#ifndef __itkNeighborhoodIterator_h |
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#define __itkNeighborhoodIterator_h |
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#include <vector> |
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#include <string.h> |
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#include <iostream> |
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#include "itkConstNeighborhoodIterator.h" |
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namespace itk { |
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/** |
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* \class NeighborhoodIterator |
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* \brief Defines iteration of a local N-dimensional neighborhood of pixels |
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* across an itk::Image. |
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* |
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* This class is a loose extension of the Standard Template Library (STL) |
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* bi-directional iterator concept to \em masks of pixel neighborhoods within |
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* itk::Image objects. This NeighborhoodIterator base class defines simple |
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* forward and reverse iteration of an N-dimensional neighborhood mask |
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* across an image. Elements within the mask can be accessed like elements |
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* within an array. |
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* |
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* NeighborhoodIterators are designed to encapsulate some of the complexity of |
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* working with image neighborhoods, complexity that would otherwise have to be |
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* managed at the algorithmic level. Use NeighborhoodIterators to simplify |
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* writing algorithms that perform geometrically localized operations on images |
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* (for example, convolution and morphological operations). |
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* |
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* To motivate the discussion of NeighborhoodIterators and their use in |
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* Itk, consider the following code that takes directional derivatives at each |
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* point in an image. |
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* |
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* \code |
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* itk::NeighborhoodInnerProduct<ImageType> IP; |
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* |
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* itk::DerivativeOperator<ImageType> operator; |
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* operator->SetOrder(1); |
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* operator->SetDirection(0); |
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* operator->CreateDirectional(); |
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* |
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* itk::NeighborhoodIterator<ImageType> |
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* iterator(operator->GetRadius(), myImage, myImage->GetRequestedRegion()); |
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* |
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* iterator.SetToBegin(); |
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* while ( ! iterator.IsAtEnd() ) |
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* { |
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** std::cout << "Derivative at index " << iterator.GetIndex() << is << |
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* IP(iterator, operator) << std::endl; |
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* ++iterator; |
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* } |
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* \endcode |
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* |
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* Most of the work for the programmer in the code above is in setting up for |
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* the iteration. There are three steps. First an inner product function |
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* object is created which will be used to effect convolution with the |
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* derivative kernel. Setting up the derivative kernel, DerivativeOperator, |
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* involves setting the order and direction of the derivative. Finally, we |
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* create an iterator over the RequestedRegion of the itk::Image (see Image) |
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* using the radius of the derivative kernel as the size. |
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* |
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* Itk iterators only loosely follow STL conventions. Notice that instead of |
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* asking myImage for myImage.begin() and myImage.end(), iterator.SetToBegin() |
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* and iterator.IsAtEnd() are called. Itk iterators are typically more complex |
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* objects than traditional, pointer-style STL iterators, and the increased |
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* overhead required to conform to the complete STL API is not always |
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* justified. |
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* |
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* The API for creating and manipulating a NeighborhoodIterator mimics |
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* that of the itk::ImageIterators. Like the itk::ImageIterator, a |
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* ConstNeighborhoodIterator is defined on a region of interest in an itk::Image. |
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* Iteration is constrained within that region of interest. |
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* |
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* A NeighborhoodIterator is constructed as a container of pointers (offsets) |
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* to a geometric neighborhood of image pixels. As the central pixel position |
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* in the mask is moved around the image, the neighboring pixel pointers |
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* (offsets) are moved accordingly. |
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* |
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* A \em pixel \em neighborhood is defined as a central pixel location and an |
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* N-dimensional radius extending outward from that location. |
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* Pixels in a neighborhood can be accessed through a NeighborhoodIterator |
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* like elements in an array. For example, a 2D neighborhood with radius 2x1 |
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* has indices: |
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* |
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* \code |
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* |
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* 0 1 2 3 4 |
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* 5 6 7 8 9 |
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* 10 11 12 13 14 |
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* |
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* \endcode |
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* |
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* Now suppose a NeighborhoodIterator with the above dimensions is constructed |
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* and positioned over a neighborhood of values in an Image: |
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* |
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* \code |
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* |
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* 1.2 1.3 1.8 1.4 1.1 |
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WCM |
* 1.8 1.1 0.7 1.0 1.0 |
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* 2.1 1.9 1.7 1.4 2.0 |
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* |
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* \endcode |
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* |
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* Shown below is some sample pixel access code and the values that it returns. |
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* |
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* \code |
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* |
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* ::size_t c = (::size_t) (iterator.Size() / 2); // get offset of center pixel |
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* ::size_t s = iterator.GetStride(1); // y-dimension step size |
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* |
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* std::cout << iterator.GetPixel(7) << std::endl; |
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* std::cout << iterator.GetCenterPixel() << std::endl; |
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* std::cout << iterator.GetPixel(c) << std::endl; |
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* std::cout << iterator.GetPixel(c-1) << std::endl; |
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* std::cout << iterator.GetPixel(c-s) << std::endl; |
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* std::cout << iterator.GetPixel(c-s-1) << std::endl; |
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* std::cout << *iterator[c] << std::endl; |
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* |
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* \endcode |
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* |
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* Results: |
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* |
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* \code |
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* 0.7 |
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* 0.7 |
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* 0.7 |
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* 1.1 |
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* 1.8 |
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* 1.3 |
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* 0.7 |
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* \endcode |
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* |
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* Use of GetPixel() is preferred over the *iterator[] form, and can be used |
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* without loss of efficiency in most cases. Some variations (subclasses) of |
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* NeighborhoodIterators may exist which do not support the latter |
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* API. Corresponding SetPixel() methods exist to modify pixel values in |
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* non-const NeighborhoodIterators. |
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* |
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* NeighborhoodIterators are "bidirectional iterators". They move only in two |
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* directions through the data set. These directions correspond to the layout |
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* of the image data in memory and not to spatial directions of the |
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* N-dimensional itk::Image. Iteration always proceeds along the fastest |
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* increasing dimension (as defined by the layout of the image data) . For |
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* itk::Image this is the first dimension specified (i.e. for 3-dimensional |
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* (x,y,z) NeighborhoodIterator proceeds along the x-dimension) (For random |
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* access iteration through N-dimensional indicies, use |
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* RandomAccessNeighborhoodIterator.) |
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* |
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* Each subclass of a ConstNeighborhoodIterator may also define its own |
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* mechanism for iteration through an image. In general, the Iterator does not |
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* directly keep track of its spatial location in the image, but uses a set of |
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* internal loop variables and offsets to trigger wraps at itk::Image region |
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* boundaries, and to identify the end of the itk::Image region. |
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* |
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* |
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* \todo Better support for regions with negative indicies. |
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* \todo Add Begin() and End() methods? |
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* |
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* \sa DerivativeOperator \sa NeighborhoodInnerProduct |
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* |
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* \par MORE INFORMATION |
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* For a complete description of the ITK Image Iterators and their API, please |
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* see the Iterators chapter in the ITK Software Guide. The ITK Software Guide |
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* is available in print and as a free .pdf download from http://www.itk.org. |
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* |
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* \ingroup ImageIterators |
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* |
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* \sa ImageConstIterator \sa ConditionalConstIterator |
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* \sa ConstNeighborhoodIterator \sa ConstShapedNeighborhoodIterator |
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* \sa ConstSliceIterator \sa CorrespondenceDataStructureIterator |
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* \sa FloodFilledFunctionConditionalConstIterator |
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* \sa FloodFilledImageFunctionConditionalConstIterator |
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* \sa FloodFilledImageFunctionConditionalIterator |
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* \sa FloodFilledSpatialFunctionConditionalConstIterator |
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* \sa FloodFilledSpatialFunctionConditionalIterator |
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* \sa ImageConstIterator \sa ImageConstIteratorWithIndex |
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* \sa ImageIterator \sa ImageIteratorWithIndex |
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* \sa ImageLinearConstIteratorWithIndex \sa ImageLinearIteratorWithIndex |
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* \sa ImageRandomConstIteratorWithIndex \sa ImageRandomIteratorWithIndex |
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* \sa ImageRegionConstIterator \sa ImageRegionConstIteratorWithIndex |
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* \sa ImageRegionExclusionConstIteratorWithIndex |
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* \sa ImageRegionExclusionIteratorWithIndex |
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* \sa ImageRegionIterator \sa ImageRegionIteratorWithIndex |
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* \sa ImageRegionReverseConstIterator \sa ImageRegionReverseIterator |
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* \sa ImageReverseConstIterator \sa ImageReverseIterator |
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* \sa ImageSliceConstIteratorWithIndex \sa ImageSliceIteratorWithIndex |
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* \sa NeighborhoodIterator \sa PathConstIterator \sa PathIterator |
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* \sa ShapedNeighborhoodIterator \sa SliceIterator |
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* \sa ImageConstIteratorWithIndex |
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* |
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* \ingroup Operators |
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*/ |
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template<class TImage, class TBoundaryCondition |
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= ZeroFluxNeumannBoundaryCondition<TImage> > |
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class ITK_EXPORT NeighborhoodIterator |
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**: public ConstNeighborhoodIterator<TImage,TBoundaryCondition> |
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{ |
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public: |
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/** Standard class typedefs. */ |
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typedef NeighborhoodIterator Self; |
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TDA |
typedef ConstNeighborhoodIterator<TImage,TBoundaryCondition> Superclass; |
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/** Extract typedefs from superclass. */ |
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typedef typename Superclass::InternalPixelType InternalPixelType; |
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TDA |
typedef typename Superclass::PixelType PixelType; |
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typedef typename Superclass::SizeType SizeType; |
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TDA |
typedef typename Superclass::ImageType ImageType; |
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TDA |
typedef typename Superclass::RegionType RegionType; |
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TDA |
typedef typename Superclass::IndexType IndexType; |
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TDA |
typedef typename Superclass::OffsetType OffsetType; |
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TDA |
typedef typename OffsetType::OffsetValueType OffsetValueType; |
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TDA |
typedef typename Superclass::RadiusType RadiusType; |
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TDA |
typedef typename Superclass::NeighborhoodType NeighborhoodType; |
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TDA |
typedef typename Superclass::Iterator Iterator; |
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TDA |
typedef typename Superclass::ConstIterator ConstIterator; |
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typedef typename Superclass::ImageBoundaryConditionPointerType |
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TDA,IND |
***ImageBoundaryConditionPointerType; |
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/** Default constructor. */ |
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NeighborhoodIterator(): Superclass() {} |
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/** Copy constructor */ |
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NeighborhoodIterator( const NeighborhoodIterator &n ) |
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****: Superclass(n) {} |
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/** Assignment operator */ |
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Self &operator=(const Self& orig) |
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{ |
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******Superclass::operator=(orig); |
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******return *this; |
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} |
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/** Constructor which establishes the region size, neighborhood, and image |
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* over which to walk. */ |
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NeighborhoodIterator(const SizeType &radius, ImageType * ptr, |
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const RegionType ®ion) |
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****: Superclass(radius, ptr, region) { } |
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/** Standard print method */ |
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virtual void PrintSelf(std::ostream &, Indent) const; |
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/** Returns the central memory pointer of the neighborhood. */ |
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InternalPixelType *GetCenterPointer() |
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{ return (this->operator[]((this->Size())>>1)); } |
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/** Returns the central pixel of the neighborhood. */ |
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virtual void SetCenterPixel(const PixelType &p) |
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**{ this->m_NeighborhoodAccessorFunctor.Set(this->operator[]((this->Size())>>1), p); } |
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/** Virtual function that replaces the pixel values in the image |
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* neighborhood that are pointed to by this NeighborhoodIterator with |
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* the pixel values contained in a Neighborhood. */ |
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virtual void SetNeighborhood(const NeighborhoodType &); |
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/** Special SetPixel method which quietly ignores out-of-bounds attempts. |
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* Sets status TRUE if pixel has been set, FALSE otherwise. */ |
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virtual void SetPixel(const unsigned i, const PixelType &v, |
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bool &status); |
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/** Set the pixel at the ith location. */ |
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virtual void SetPixel(const unsigned i, const PixelType &v); |
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// { *(this->operator[](i)) = v; } |
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/** Set the pixel at offset o from the neighborhood center */ |
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virtual void SetPixel(const OffsetType o, const PixelType &v) |
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**{ this->SetPixel(this->GetNeighborhoodIndex(o), v); } |
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****// { *(this->operator[](o)) = v; } |
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/** Sets the pixel value located i pixels distant from the neighborhood center in |
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******the positive specified ``axis'' direction. No bounds checking is done on |
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******the size of the neighborhood. */ |
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virtual void SetNext(const unsigned axis, const unsigned i, |
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const PixelType &v) |
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**{ this->SetPixel(this->GetCenterNeighborhoodIndex() |
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*********************+ (i * this->GetStride(axis)), v); } |
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/** Sets the pixel value located one pixel distant from the neighborhood center in |
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******the specifed positive axis direction. No bounds checking is done on the |
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******size of the neighborhood. */ |
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virtual void SetNext(const unsigned axis, const PixelType &v) |
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{ this->SetPixel(this->GetCenterNeighborhoodIndex() |
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***********************+ this->GetStride(axis), v); } |
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/** Sets the pixel value located i pixels distant from the neighborhood center in |
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******the negative specified ``axis'' direction. No bounds checking is done on |
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******the size of the neighborhood. */ |
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virtual void SetPrevious(const unsigned axis, const unsigned i, |
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const PixelType &v) |
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{ this->SetPixel(this->GetCenterNeighborhoodIndex() |
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*********************- (i * this->GetStride(axis)), v); } |
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/** Sets the pixel value located one pixel distant from the neighborhood center in |
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******the specifed negative axis direction. No bounds checking is done on the |
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******size of the neighborhood. */ |
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virtual void SetPrevious(const unsigned axis, |
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const PixelType &v) |
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{ this->SetPixel(this->GetCenterNeighborhoodIndex() |
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*********************- this->GetStride(axis), v); } |
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}; |
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} // namespace itk |
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#ifndef ITK_MANUAL_INSTANTIATION |
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#include "itkNeighborhoodIterator.txx" |
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#endif |
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#endif |
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