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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: $RCSfile: itkAdaptiveHistogramEqualizationImageFilter.h,v $
Language: C++
Date: $Date: 2003-09-10 14:28:43 $
Version: $Revision: 1.19 $
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.
=========================================================================*/
#ifndef __itkAdaptiveHistogramEqualizationImageFilter_h
#define __itkAdaptiveHistogramEqualizationImageFilter_h
#include <itkImageToImageFilter.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
*/
template <class TImageType>
class ITK_EXPORT AdaptiveHistogramEqualizationImageFilter :
public ImageToImageFilter< 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);
itkGetMacro(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);
itkGetMacro(Beta, float);
/** Set/Get the radius of the neighborhood used to compute local
* statistics. Radius sizes of 10 and 20 are common. Default is a
* radius of 5. */
itkSetMacro(Radius, ImageSizeType);
itkGetConstReferenceMacro(Radius, ImageSizeType);
/** Set/Get whether an optimized lookup table for the intensity
* mapping function is used. Default is off. */
itkSetMacro(UseLookupTable, bool);
itkGetMacro(UseLookupTable, bool);
itkBooleanMacro(UseLookupTable);
protected:
AdaptiveHistogramEqualizationImageFilter()
{
m_Alpha = .3;
m_Beta = .3;
m_Radius.Fill( 5 );
m_UseLookupTable = false;
}
virtual ~AdaptiveHistogramEqualizationImageFilter(){}
void PrintSelf(std::ostream& os, Indent indent) const;
/** Standard pipeline method.*/
void GenerateData();
/** Adaptive histogram equalization requires more input that it
* outputs. It needs request an input region that is padded by the
* radius.
* \sa ProcessObject::GenerateInputRequestedRegion() */
void GenerateInputRequestedRegion();
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;
/** The window size of the adaptive algorithm. This parameter
* defines the size of neighborhood around the evaluated pixel. */
ImageSizeType m_Radius;
/** 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.txx"
#endif
#endif
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