Orfeo Toolbox  3.20
DataRepresentation/Image/Image1.cxx
/*=========================================================================
Program: ORFEO Toolbox
Language: C++
Date: $Date$
Version: $Revision$
Some parts of this code are derived from ITK. See ITKCopyright.txt
for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
=========================================================================*/
// Software Guide : BeginLatex
//
// This example illustrates how to manually construct an \doxygen{otb}{Image}
// class. The following is the minimal code needed to instantiate, declare
// and create the image class.
//
// \index{Image!Instantiation}
//
// First, the header file of the Image class must be included.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "otbImage.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 image class. Here we create
// a 2D image, which is what we often use in remote sensing
// applications, anyway, with \code{unsigned short} pixel data.
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
typedef otb::Image<unsigned short, 2> 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{itk}{SmartPointer}.
//
// \index{Image!Pointer}
// \index{Image!New()}
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
ImageType::Pointer image = ImageType::New();
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// In OTB, 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 OTB 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 OTB, 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{itk}{Index} and
// \doxygen{itk}{Size} classes. The origin of the region within the
// image with which it is associated is defined by Index. The
// extent, or size, of the region is defined by Size. 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. 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 starting point of the image is defined by an Index class
// that is an n-dimensional array where each component is an integer
// indicating the grid coordinates of the initial pixel of the image.
//
// \index{Image!Size}
// \index{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
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// The region size is represented by an array of the same dimension of the
// image (using the Size class). The components of the array are
// unsigned integers indicating the extent in pixels of the image along
// every dimension.
//
// \index{Image!Index}
// \index{Image!IndexType}
//
// Software Guide : EndLatex
//
// Software Guide : BeginCodeSnippet
ImageType::SizeType size;
size[0] = 200; // size along X
size[1] = 200; // size along Y
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// Having defined the starting index and the image size, these two
// parameters are used to create an ImageRegion object which basically
// encapsulates both concepts. The region is initialized with the
// starting index and size of the image.
//
// \index{Image!itk::ImageRegion}
// \index{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 LargestPossibleRegion, BufferedRegion, and
// 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{Image!Allocate()}
// \index{Image!SetRegions()}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
image->SetRegions(region);
image->Allocate();
// Software Guide : EndCodeSnippet
return EXIT_SUCCESS;
}

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