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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: itkHessianRecursiveGaussianFilterScaleSpaceTest.cxx
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) Insight Software Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#if defined(_MSC_VER)
#pragma warning ( disable : 4786 )
#endif
#include <itkImage.h>
#include <itkHessianRecursiveGaussianImageFilter.h>
#include <itkImageRegionIteratorWithIndex.h>
// This test creates an image varying as a 1D Gaussian in the X direction
// for different values of sigma, and checks the scale-space response of
// the xx component of the Hessian at the center of the Gaussian.
// If NormalizeAcrossScale works correctly, the filter should yield the
// same Hxx across different scales.
int itkHessianRecursiveGaussianFilterScaleSpaceTest(int, char* [] )
{
const unsigned int Dimension = 3;
typedef double PixelType;
typedef itk::Image<PixelType,Dimension> ImageType;
typedef itk::Index<Dimension> IndexType;
typedef itk::Size<Dimension> SizeType;
typedef itk::ImageRegion<Dimension> RegionType;
typedef ImageType::PointType PointType;
typedef ImageType::SpacingType SpacingType;
ImageType::Pointer inputImage = ImageType::New();
SizeType size;
size.Fill(21);
size[0] = 401;
IndexType start;
start.Fill(0);
RegionType region;
region.SetIndex(start);
region.SetSize(size);
PointType origin;
origin.Fill(-1.25);
origin[0] = -20.0;
SpacingType spacing;
spacing.Fill(0.1);
inputImage->SetOrigin(origin);
inputImage->SetSpacing(spacing);
inputImage->SetLargestPossibleRegion(region);
inputImage->SetBufferedRegion(region);
inputImage->SetRequestedRegion(region);
inputImage->Allocate();
typedef itk::ImageRegionIteratorWithIndex<ImageType> IteratorType;
const unsigned int numberOfScales = 4;
double scales[numberOfScales];
scales[0] = 1.0;
scales[1] = 2.0;
scales[2] = 3.0;
scales[3] = 5.0;
for (unsigned int i=0; i<numberOfScales; i++)
{
IteratorType it(inputImage, inputImage->GetRequestedRegion());
PointType point;
double objectSize = scales[i];
// Fill the image with a 1D Gaussian along X with sigma equal to the current scale
// The Gaussian is not normalized, since it should have the same peak value across
// scales, only sigma should change
while(!it.IsAtEnd())
{
inputImage->TransformIndexToPhysicalPoint(it.GetIndex(),point);
double value = vcl_exp(-point[0]*point[0] / (2.0*objectSize*objectSize));
it.Set(value);
++it;
}
// Compute the hessian using NormalizeAcrossScale true
typedef itk::HessianRecursiveGaussianImageFilter<ImageType> FilterType;
typedef FilterType::OutputImageType HessianImageType;
FilterType::Pointer filter = FilterType::New();
filter->SetInput(inputImage);
filter->SetSigma(objectSize);
filter->SetNormalizeAcrossScale(true);
filter->Update();
HessianImageType::Pointer outputImage = filter->GetOutput();
// Get the value at the center of the image, the location of the peak of the Gaussian
PointType center;
center.Fill(0.0);
IndexType centerIndex;
typedef HessianImageType::PixelType HessianType;
outputImage->TransformPhysicalPointToIndex(center,centerIndex);
// Irrespective of the scale, the Hxx component should be the same
double centerHxx = outputImage->GetPixel(centerIndex)[0];
if (centerHxx > -35.46 || centerHxx < -35.47)
{
return EXIT_FAILURE;
}
}
return EXIT_SUCCESS;
}
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