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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.
*
*=========================================================================*/
#ifndef itkGradientImageFilter_h
#define itkGradientImageFilter_h
#include "itkImageToImageFilter.h"
#include "itkCovariantVector.h"
#include "itkImageRegionIterator.h"
namespace itk
{
template <typename TPixelType, unsigned int VImageDimension > class VectorImage;
/** \class GradientImageFilter
* \brief Computes the gradient of an image using directional derivatives.
*
* Computes the gradient of an image using directional derivatives.
* The directional derivative at each pixel location is computed by
* convolution with a first-order derivative operator.
*
* The second template parameter defines the value type used in the
* derivative operator (defaults to float). The third template
* parameter defines the value type used for output image (defaults to
* float). The output image is defined as a covariant vector image
* whose value type is specified as this third template parameter.
*
*
* \sa Image
* \sa Neighborhood
* \sa NeighborhoodOperator
* \sa NeighborhoodIterator
*
* \ingroup GradientFilters
* \ingroup ITKImageGradient
*/
template< typename TInputImage,
typename TOperatorValueType = float,
typename TOutputValueType = float,
typename TOutputImageType = Image< CovariantVector< TOutputValueType,
TInputImage::ImageDimension >,
TInputImage::ImageDimension > >
class ITK_TEMPLATE_EXPORT GradientImageFilter:
public ImageToImageFilter< TInputImage, TOutputImageType >
{
public:
/** Extract dimension from input image. */
itkStaticConstMacro(InputImageDimension, unsigned int,
TInputImage::ImageDimension);
itkStaticConstMacro(OutputImageDimension, unsigned int,
TOutputImageType::ImageDimension);
/** Convenient typedefs for simplifying declarations. */
typedef TInputImage InputImageType;
typedef typename InputImageType::Pointer InputImagePointer;
typedef TOutputImageType OutputImageType;
typedef typename OutputImageType::Pointer OutputImagePointer;
/** Standard class typedefs. */
typedef GradientImageFilter Self;
typedef ImageToImageFilter< InputImageType, OutputImageType > Superclass;
typedef SmartPointer< Self > Pointer;
typedef SmartPointer< const Self > ConstPointer;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** Run-time type information (and related methods). */
itkTypeMacro(GradientImageFilter, ImageToImageFilter);
/** Image typedef support. */
typedef typename InputImageType::PixelType InputPixelType;
typedef TOperatorValueType OperatorValueType;
typedef TOutputValueType OutputValueType;
typedef typename OutputImageType::PixelType OutputPixelType;
typedef CovariantVector<
OutputValueType, itkGetStaticConstMacro(OutputImageDimension) >
CovariantVectorType;
typedef typename OutputImageType::RegionType OutputImageRegionType;
/** GradientImageFilter needs a larger input requested region than
* the output requested region. As such, GradientImageFilter needs
* to provide an implementation for GenerateInputRequestedRegion()
* in order to inform the pipeline execution model.
*
* \sa ImageToImageFilter::GenerateInputRequestedRegion() */
virtual void GenerateInputRequestedRegion() ITK_OVERRIDE;
/** Use the image spacing information in calculations. Use this option if you
* want derivatives in physical space. Default is UseImageSpacingOn. */
void SetUseImageSpacingOn()
{ this->SetUseImageSpacing(true); }
/** Ignore the image spacing. Use this option if you want derivatives in
isotropic pixel space. Default is UseImageSpacingOn. */
void SetUseImageSpacingOff()
{ this->SetUseImageSpacing(false); }
/** Set/Get whether or not the filter will use the spacing of the input
image in its calculations */
itkSetMacro(UseImageSpacing, bool);
itkGetConstMacro(UseImageSpacing, bool);
itkBooleanMacro(UseImageSpacing);
/** Allows to change the default boundary condition */
void OverrideBoundaryCondition(ImageBoundaryCondition< TInputImage >* boundaryCondition);
#ifdef ITK_USE_CONCEPT_CHECKING
// Begin concept checking
itkConceptMacro( InputConvertibleToOutputCheck,
( Concept::Convertible< InputPixelType, OutputValueType > ) );
itkConceptMacro( OutputHasNumericTraitsCheck,
( Concept::HasNumericTraits< OutputValueType > ) );
// End concept checking
#endif
/** The UseImageDirection flag determines whether image derivatives are
* computed with respect to the image grid or with respect to the physical
* space. When this flag is ON the derivatives are computed with respect to
* the coordinate system of physical space. The difference is whether we take
* into account the image Direction or not. The flag ON will take into
* account the image direction and will result in an extra matrix
* multiplication compared to the amount of computation performed when the
* flag is OFF.
* The default value of this flag is On.
*/
itkSetMacro(UseImageDirection, bool);
itkGetConstMacro(UseImageDirection, bool);
itkBooleanMacro(UseImageDirection);
protected:
GradientImageFilter();
virtual ~GradientImageFilter() ITK_OVERRIDE;
void PrintSelf(std::ostream & os, Indent indent) const ITK_OVERRIDE;
/** GradientImageFilter can be implemented as a multithreaded filter.
* Therefore, this implementation provides a ThreadedGenerateData()
* routine which is called for each processing thread. The output
* image data is allocated automatically by the superclass prior to
* calling ThreadedGenerateData(). ThreadedGenerateData can only
* write to the portion of the output image specified by the
* parameter "outputRegionForThread"
*
* \sa ImageToImageFilter::ThreadedGenerateData(),
* ImageToImageFilter::GenerateData() */
void ThreadedGenerateData(const OutputImageRegionType & outputRegionForThread,
ThreadIdType threadId) ITK_OVERRIDE;
private:
ITK_DISALLOW_COPY_AND_ASSIGN(GradientImageFilter);
virtual void GenerateOutputInformation() ITK_OVERRIDE;
// An overloaded method which may transform the gradient to a
// physical vector and converts to the correct output pixel type.
template <typename TValue>
void SetOutputPixel( ImageRegionIterator< VectorImage<TValue,OutputImageDimension> > &it, CovariantVectorType &gradient )
{
if ( this->m_UseImageDirection )
{
CovariantVectorType physicalGradient;
it.GetImage()->TransformLocalVectorToPhysicalVector( gradient, physicalGradient );
it.Set( OutputPixelType( physicalGradient.GetDataPointer(), InputImageDimension, false ) );
}
else
{
it.Set( OutputPixelType( gradient.GetDataPointer(), InputImageDimension, false ) );
}
}
template <typename T >
void SetOutputPixel( ImageRegionIterator< T > &it, CovariantVectorType &gradient )
{
// This uses the more efficient set by reference method
if ( this->m_UseImageDirection )
{
it.GetImage()->TransformLocalVectorToPhysicalVector( gradient, it.Value() );
}
else
{
it.Value() = gradient;
}
}
bool m_UseImageSpacing;
// flag to take or not the image direction into account
// when computing the derivatives.
bool m_UseImageDirection;
// allow setting the the m_BoundaryCondition
ImageBoundaryCondition< TInputImage, TInputImage >* m_BoundaryCondition;
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
#include "itkGradientImageFilter.hxx"
#endif
#endif
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