Examples/SpatialObjects/SpatialObjectToImageStatisticsCalculator.cxx

/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://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
//
// \index{itk::Spatial\-Object\-To\-Image\-Statistics\-Calculator}
// This example describes how to use the
// \doxygen{SpatialObjectToImageStatisticsCalculator} to compute statistics
// of an \doxygen{Image} only in a region defined inside a given
// \doxygen{SpatialObject}.
//
// Software Guide : EndLatex
 
// Software Guide : BeginCodeSnippet
#include "itkSpatialObjectToImageStatisticsCalculator.h"
// Software Guide : EndCodeSnippet
 
#include "itkImage.h"
#include "itkEllipseSpatialObject.h"
#include "itkRandomImageSource.h"
 
int
main(int, char *[])
{
  // Software Guide : BeginLatex
  //
  // We first create a test image using the \doxygen{RandomImageSource}
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using ImageType = itk::Image<unsigned char, 2>;
  using RandomImageSourceType = itk::RandomImageSource<ImageType>;
  auto                     randomImageSource = RandomImageSourceType::New();
  ImageType::SizeValueType size[2];
  size[0] = 10;
  size[1] = 10;
  randomImageSource->SetSize(size);
  randomImageSource->Update();
  const ImageType::Pointer image = randomImageSource->GetOutput();
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // Next we create an \doxygen{EllipseSpatialObject} with a radius of 2.
  // We also move the ellipse to the center of the image.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using EllipseType = itk::EllipseSpatialObject<2>;
  auto ellipse = EllipseType::New();
  ellipse->SetRadiusInObjectSpace(2);
  auto offset = itk::MakeFilled<EllipseType::PointType>(5);
  ellipse->SetCenterInObjectSpace(offset);
  ellipse->Update();
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // Then we can create the
  // \doxygen{SpatialObjectToImageStatisticsCalculator}.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using CalculatorType =
    itk::SpatialObjectToImageStatisticsCalculator<ImageType, EllipseType>;
  auto calculator = CalculatorType::New();
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // We pass a pointer to the image to the calculator.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  calculator->SetImage(image);
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // We also pass the SpatialObject. The statistics will be computed inside
  // the SpatialObject (Internally the calculator is using the
  // \code{IsInside()} function).
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  calculator->SetSpatialObject(ellipse);
  // Software Guide : EndCodeSnippet
 
  // Software Guide : BeginLatex
  //
  // At the end we trigger the computation via the \code{Update()} function
  // and we can retrieve the mean and the covariance matrix using
  // \code{GetMean()} and \code{GetCovarianceMatrix()} respectively.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  calculator->Update();
  std::cout << "Sample mean = " << calculator->GetMean() << std::endl;
  std::cout << "Sample covariance = " << calculator->GetCovarianceMatrix();
  // Software Guide : EndCodeSnippet
 
  return EXIT_SUCCESS;
}