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itkFrequencyDomain1DFilterFunction.h
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itkFrequencyDomain1DFilterFunction.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 itkFrequencyDomain1DFilterFunction_h
#define itkFrequencyDomain1DFilterFunction_h
#include "itkObject.h"
#include "itkObjectFactory.h"
namespace itk
{
/** \class FrequencyDomain1DFilterFunction
* \brief
* Class to implment filter functions for FrequencyDomain1DImageFilter
*
* Supports caching of precomputed function values (SetUseCache) for applying
* the function to multiple signals of the same length.
* For the caching to work properly make sure this->Modified gets called in subclasses
* whenever a parmater is changed that changes the function values.
*
* \ingroup FourierTransform
* \ingroup Ultrasound
*/
class FrequencyDomain1DFilterFunction : public Object
{
public:
/** Standard class type alias. */
using Self = FrequencyDomain1DFilterFunction;
using Superclass = Object;
using Pointer = SmartPointer<Self>;
using ConstPointer = SmartPointer<const Self>;
itkTypeMacro(FrequencyDomain1DFilterFunction, Object);
itkNewMacro(Self);
/** discrete frequency index such as retunr by FFTW, i.e.
* 0 is DC component
* i / SignalSize * 2*pi is the frequency,
* i.e., first half positive frequencies and
* second half negative frequencies in reverse order.
*/
double
EvaluateIndex(SizeValueType & i) const
{
if (m_UseCache)
{
// TODO: Check for out of bounds?
return m_Cache[i];
}
else
{
return this->EvaluateFrequency(this->GetFrequency(i));
}
}
void
SetSignalSize(const SizeValueType & size)
{
if (this->m_SignalSize != size)
{
this->m_SignalSize = size;
if (this->m_UseCache)
{
this->m_Cache.resize(size);
}
this->Modified();
}
}
SizeValueType
GetSignalSize() const
{
return m_SignalSize;
}
itkSetMacro(UseCache, bool);
itkGetMacro(UseCache, bool);
/**
* Override this function to implement a specific filter.
* The input ranges from -1 to 1
* Default is identity function.
*/
virtual double
EvaluateFrequency(double itkNotUsed(frequency)) const
{
return 1.0;
}
virtual void
Modified() const override
{
// Force a chache update
const_cast<FrequencyDomain1DFilterFunction *>(this)->UpdateCache();
Superclass::Modified();
}
protected:
virtual void
PrintSelf(std::ostream & os, Indent indent) const override
{
Superclass::PrintSelf(os, indent);
os << indent << "SignalSize: " << m_SignalSize << std::endl;
os << indent << "UseCache: " << m_UseCache << std::endl;
os << indent << "CacheSize: " << m_Cache.size() << std::endl;
}
FrequencyDomain1DFilterFunction()
{
m_UseCache = true;
m_SignalSize = 0;
}
private:
double
GetFrequency(SizeValueType & i) const
{
double f = (2.0 * i) / m_SignalSize;
if (f > 1.0)
{
f = f - 2.0;
}
return f;
}
void
UpdateCache()
{
if (this->m_UseCache)
{
for (SizeValueType i = 0; i < m_Cache.size(); i++)
{
this->m_Cache[i] = this->EvaluateFrequency(this->GetFrequency(i));
}
}
}
bool m_UseCache;
std::vector<double> m_Cache;
SizeValueType m_SignalSize;
};
} // namespace itk
#endif // itkFrequencyDomain1DFilterFunction.h