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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
//
// Many image processing tasks require images of non-scalar pixel type. A
// typical example is an image of vectors. This is the image type required to
// represent the gradient of a scalar image. The following code illustrates
// how to instantiate and use an image whose pixels are of vector type.
//
// For convenience we use the \doxygen{Vector} class to define the pixel
// type. The Vector class is intended to represent a geometrical vector in
// space. It is not intended to be used as an array container like the
// \href{http://www.sgi.com/tech/stl/Vector.html}{\code{std::vector}} in
// \href{http://www.sgi.com/tech/stl/}{STL}. If you are interested in
// containers, the \doxygen{VectorContainer} class may provide the
// functionality you want.
//
// \index{itk::Vector}
// \index{itk::Vector!header}
//
//
// The first step is to include the header file of the Vector class.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
#include "itkVector.h"
// Software Guide : EndCodeSnippet
#include "itkImage.h"
int main(int, char *[])
{
// Software Guide : BeginLatex
//
// The Vector class is templated over the type used to represent
// the coordinate in space and over the dimension of the space. In this example,
// we want the vector dimension to match the image dimension, but this is by
// no means a requirement. We could have defined a four-dimensional image
// with three-dimensional vectors as pixels.
//
// \index{itk::Vector!Instantiation}
// \index{itk::Vector!itk::Image}
// \index{itk::Image!Vector pixel}
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
typedef itk::Vector< float, 3 > PixelType;
typedef itk::Image< PixelType, 3 > ImageType;
// Software Guide : EndCodeSnippet
// Then the image object can be created
ImageType::Pointer image = ImageType::New();
// The image region should be initialized
const ImageType::IndexType start = {{0,0,0}}; //First index at {X,Y,Z}
const ImageType::SizeType size = {{200,200,200}}; //Size of {X,Y,Z}
ImageType::RegionType region;
region.SetSize( size );
region.SetIndex( start );
// Pixel data is allocated
image->SetRegions( region );
image->Allocate();
// The image buffer is initialized to a particular value
ImageType::PixelType initialValue;
// A vector can initialize all its components to the
// same value by using the Fill() method.
initialValue.Fill( 0.0 );
// Now the image buffer can be initialized with this
// vector value.
image->FillBuffer( initialValue );
const ImageType::IndexType pixelIndex = {{27,29,37}}; //Position {X,Y,Z}
// Software Guide : BeginLatex
//
// The Vector class inherits the operator \code{[]} from the
// \doxygen{FixedArray} class. This makes it possible to access the
// Vector's components using index notation.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
ImageType::PixelType pixelValue;
pixelValue[0] = 1.345; // x component
pixelValue[1] = 6.841; // y component
pixelValue[2] = 3.295; // x component
// Software Guide : EndCodeSnippet
// Software Guide : BeginLatex
//
// We can now store this vector in one of the image pixels by defining an
// index and invoking the \code{SetPixel()} method.
//
// Software Guide : EndLatex
// Software Guide : BeginCodeSnippet
image->SetPixel( pixelIndex, pixelValue );
// Software Guide : EndCodeSnippet
// The GetPixel method can also be used to read Vectors
// pixels from the image
ImageType::PixelType value = image->GetPixel( pixelIndex );
std::cout << value << std::endl;
// Lets repeat that both \code{SetPixel()} and \code{GetPixel()} are
// inefficient and should only be used for debugging purposes or for
// implementing interactions with a graphical user interface such as
// querying pixel value by clicking with the mouse.
return EXIT_SUCCESS;
}
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