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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 __itkAdaptiveHistogramEqualizationImageFilter_h
#define __itkAdaptiveHistogramEqualizationImageFilter_h
#include "itkBoxImageFilter.h"
#include "itkImage.h"
namespace itk
{
/**
* \class AdaptiveHistogramEqualizationImageFilter
* \brief Power Law Adaptive Histogram Equalization
*
* Histogram equalization modifies the contrast in an image. The
* AdaptiveHistogramEqualizationImageFilter is a superset of many
* contrast enhancing filters. By modifying its parameters (alpha,
* beta, and window), the AdaptiveHistogramEqualizationImageFilter can
* produce an adaptively equalized histogram or a version of unsharp
* mask (local mean subtraction). Instead of applying a strict
* histogram equalization in a window about a pixel, this filter
* prescribes a mapping function (power law) controlled by the
* parameters alpha and beta.
*
* The parameter alpha controls how much the filter acts like the
* classical histogram equalization method (alpha=0) to how
* much the filter acts like an unsharp mask (alpha=1).
*
* The parameter beta controls how much the filter acts like an
* unsharp mask (beta=0) to much the filter acts like pass through
* (beta=1, with alpha=1).
*
* The parameter window controls the size of the region over which
* local statistics are calculated.
*
* By altering alpha, beta and window, a host of equalization and unsharp
* masking filters is available.
*
* For detail description, reference "Adaptive Image Contrast
* Enhancement using Generalizations of Histogram Equalization."
* J.Alex Stark. IEEE Transactions on Image Processing, May 2000.
*
* \ingroup ImageEnhancement
* \ingroup ITKImageStatistics
*
* \wiki
* \wikiexample{NeedDemo/ImageProcessing/AdaptiveHistogramEqualizationImageFilter,Adaptive histogram equalization}
* \endwiki
*/
template< typename TImageType >
class AdaptiveHistogramEqualizationImageFilter:
public BoxImageFilter< TImageType, TImageType >
{
public:
/**
* Standard class typedefs
*/
typedef AdaptiveHistogramEqualizationImageFilter Self;
typedef ImageToImageFilter< TImageType, TImageType > Superclass;
typedef SmartPointer< Self > Pointer;
typedef SmartPointer< const Self > ConstPointer;
itkStaticConstMacro(ImageDimension, unsigned int,
TImageType::ImageDimension);
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** Run-time type information (and related methods). */
itkTypeMacro(AdaptiveHistogramEqualizationImageFilter, ImageToImageFilter);
/** Image type typedef support. */
typedef TImageType ImageType;
typedef typename ImageType::SizeType ImageSizeType;
/** Set/Get the value of alpha. Alpha=0 produces the adaptive
* histogram equalization (provided beta=0). Alpha=1 produces an
* unsharp mask. Default is 0.3. */
itkSetMacro(Alpha, float);
itkGetConstMacro(Alpha, float);
/** Set/Get the value of beta. If beta=1 (and alpha=1),
* then the output image matches the input image. As beta
* approaches 0, the filter behaves as an unsharp mask. Default is
* 0.3. */
itkSetMacro(Beta, float);
itkGetConstMacro(Beta, float);
/** Set/Get whether an optimized lookup table for the intensity
* mapping function is used. Default is off. */
itkSetMacro(UseLookupTable, bool);
itkGetConstMacro(UseLookupTable, bool);
itkBooleanMacro(UseLookupTable);
protected:
AdaptiveHistogramEqualizationImageFilter()
{
m_Alpha = .3;
m_Beta = .3;
this->SetRadius(5);
m_UseLookupTable = false;
}
virtual ~AdaptiveHistogramEqualizationImageFilter(){}
void PrintSelf(std::ostream & os, Indent indent) const;
/**
* Standard pipeline method
*/
void GenerateData();
private:
AdaptiveHistogramEqualizationImageFilter(const Self &); //purposely not
// implemented
void operator=(const Self &); //purposely not
// implemented
/** The beta parameter of the AdaptiveHistogramEqualization. */
float m_Alpha;
/** The alpha parameter of the AdaptiveHistogramEqualization. */
float m_Beta;
/** Should we use a lookup table to optimize the use of the
* intensity mapping function? */
bool m_UseLookupTable;
/** A function which is used in GenerateData(). */
float CumulativeFunction(float u, float v);
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
#include "itkAdaptiveHistogramEqualizationImageFilter.hxx"
#endif
#endif
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