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/*=========================================================================
*
* Copyright Insight Software Consortium
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
// Software Guide : BeginLatex
//
// This example illustrates how to manually construct an \doxygen{Image}
// class. The following is the minimal code needed to instantiate, declare
// and create the \code{Image} class.
//
// \index{itk::Image!Instantiation}
// \index{itk::Image!Header}
//
// First, the header file of the \code{Image} class must be included.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "itkImage.h"
// Software Guide : EndCodeSnippet
int main(int, char *[])
{
// Software Guide : BeginLatex
//
// Then we must decide with what type to represent the pixels
// and what the dimension of the image will be. With these two
// parameters we can instantiate the \code{Image} class. Here we create
// a 3D image with \code{unsigned short} pixel data.
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
typedef itk::Image< unsigned short, 3 > ImageType;
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The image can then be created by invoking the \code{New()} operator
// from the corresponding image type and assigning the result
// to a \doxygen{SmartPointer}.
//
// \index{itk::Image!Pointer}
// \index{itk::Image!New()}
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
ImageType::Pointer image = ImageType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// In ITK, images exist in combination with one or more
// \emph{regions}. A region is a subset of the image and indicates a
// portion of the image that may be processed by other classes in
// the system. One of the most common regions is the
// \emph{LargestPossibleRegion}, which defines the image in its
// entirety. Other important regions found in ITK are the
// \emph{BufferedRegion}, which is the portion of the image actually
// maintained in memory, and the \emph{RequestedRegion}, which is
// the region requested by a filter or other class when operating on
// the image.
//
// In ITK, manually creating an image requires that the image is
// instantiated as previously shown, and that regions describing the image are
// then associated with it.
//
// A region is defined by two classes: the \doxygen{Index} and
// \doxygen{Size} classes. The origin of the region within the
// image is defined by the \code{Index}. The extent, or size, of the region
// is defined by the \code{Size}. When an image is created manually, the user
// is responsible for defining the image size and the index at which the
// image grid starts. These two parameters make it possible to process
// selected regions.
//
// The \code{Index} is represented by a n-dimensional array where each
// component is an integer
// indicating---in topological image coordinates---the initial pixel
// of the image.
//
// \index{itk::Image!Size}
// \index{itk::Image!SizeType}
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
ImageType::IndexType start;
start[0] = 0; // first index on X
start[1] = 0; // first index on Y
start[2] = 0; // first index on Z
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The region size is represented by an array of the same dimension as the
// image (using the \doxygen{Size} class). The components of the array are
// unsigned integers indicating the extent in pixels of the image along
// every dimension.
//
// \index{itk::Image!Index}
// \index{itk::Image!IndexType}
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
ImageType::SizeType size;
size[0] = 200; // size along X
size[1] = 200; // size along Y
size[2] = 200; // size along Z
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Having defined the starting index and the image size, these two
// parameters are used to create an \doxygen{ImageRegion} object
// which basically encapsulates both concepts.
// The region is initialized with the starting index and size of the
// image.
//
// \index{itk::Image!itk::ImageRegion}
// \index{itk::Image!RegionType}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ImageType::RegionType region;
region.SetSize( size );
region.SetIndex( start );
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Finally, the region is passed to the \code{Image} object in order to define its
// extent and origin. The \code{SetRegions} method sets the
// \emph{LargestPossibleRegion}, \emph{BufferedRegion}, and \emph{RequestedRegion}
// simultaneously. Note that none of the operations performed to this point
// have allocated memory for the image pixel data. It is necessary to
// invoke the \code{Allocate()} method to do this. Allocate does not
// require any arguments since all the information needed for memory
// allocation has already been provided by the region.
//
// \index{itk::Image!Allocate()}
// \index{itk::Image!SetRegions()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
image->SetRegions( region );
image->Allocate();
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}
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