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itkAnalyticSignalImageFilter.h
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itkAnalyticSignalImageFilter.h
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/*=========================================================================
*
* 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.
*
*=========================================================================*/
#ifndef itkAnalyticSignalImageFilter_h
#define itkAnalyticSignalImageFilter_h
#include <complex>
#include "itkComplexToComplex1DFFTImageFilter.h"
#include "itkForward1DFFTImageFilter.h"
#include "itkFrequencyDomain1DImageFilter.h"
namespace itk
{
/** \class AnalyticSignalImageFilter
* \brief Generates the analytic signal from one direction of an image.
*
* This filter generates the complex valued analytic signal along one direction
* of an image. This input is a real valued image, and the output is a complex
* image.
*
* The analytic signal is given by
*
* f_a(x) = f(x) - i f_H(x)
*
* Where i is the square root of one and f_H(x) is the Hibert transform of f(x).
*
* Since the Hilbert transform in the Fourier domain is
*
* F_H(k) = F(k) i sign(k),
*
* f_a(x) is calculated by
*
* f_a(x) = F^{-1}( F(k) 2 U(k) )
*
* where U(k) is the unit step function.
*
* \ingroup FourierTransform
* \ingroup Ultrasound
*/
template <typename TInputImage, typename TOutputImage>
class ITK_TEMPLATE_EXPORT AnalyticSignalImageFilter : public ImageToImageFilter<TInputImage, TOutputImage>
{
public:
ITK_DISALLOW_COPY_AND_ASSIGN(AnalyticSignalImageFilter);
/** Standard class type alias. */
using InputImageType = TInputImage;
using OutputImageType = TOutputImage;
using OutputImageRegionType = typename OutputImageType::RegionType;
itkStaticConstMacro(ImageDimension, unsigned int, InputImageType::ImageDimension);
using Self = AnalyticSignalImageFilter;
using Superclass = ImageToImageFilter<InputImageType, OutputImageType>;
using Pointer = SmartPointer<Self>;
using ConstPointer = SmartPointer<const Self>;
itkTypeMacro(AnalyticSignalImageFilter, ImageToImageFilter);
itkNewMacro(Self);
using FrequencyFilterType = FrequencyDomain1DImageFilter<OutputImageType, OutputImageType>;
/** Get the direction in which the filter is to be applied. */
virtual unsigned int
GetDirection() const
{
return this->m_FFTRealToComplexFilter->GetDirection();
}
/** Set the direction in which the filter is to be applied. */
virtual void
SetDirection(const unsigned int direction)
{
if (this->m_FFTRealToComplexFilter->GetDirection() != direction)
{
this->m_FFTRealToComplexFilter->SetDirection(direction);
this->m_FFTComplexToComplexFilter->SetDirection(direction);
if (this->m_FrequencyFilter.IsNotNull())
{
this->m_FrequencyFilter->SetDirection(direction);
}
this->Modified();
}
}
virtual void
SetFrequencyFilter(FrequencyFilterType * filter)
{
if (filter != this->m_FrequencyFilter.GetPointer())
{
this->m_FrequencyFilter = filter;
this->m_FrequencyFilter->SetDirection(this->GetDirection());
this->Modified();
}
}
protected:
AnalyticSignalImageFilter();
~AnalyticSignalImageFilter() override = default;
void
PrintSelf(std::ostream & os, Indent indent) const override;
// These behave like their analogs in Forward1DFFTImageFilter.
void
GenerateInputRequestedRegion() override;
void
EnlargeOutputRequestedRegion(DataObject * output) override;
void
GenerateData() override;
using FFTRealToComplexType = Forward1DFFTImageFilter<InputImageType, OutputImageType>;
typename FFTRealToComplexType::Pointer m_FFTRealToComplexFilter;
using FFTComplexToComplexType = ComplexToComplex1DFFTImageFilter<OutputImageType, OutputImageType>;
typename FFTComplexToComplexType::Pointer m_FFTComplexToComplexFilter;
private:
typename FrequencyFilterType::Pointer m_FrequencyFilter;
};
} // namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
# include "itkAnalyticSignalImageFilter.hxx"
#endif
#endif // itkAnalyticSignalImageFilter_h