Manipulates raster pixel values so that they enhanceContrast or clip into a specified numerical range according to the specified ContrastEnhancementAlgorithm. More...

#include <qgscontrastenhancement.h>

Collaboration diagram for QgsContrastEnhancement:

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Public Types
enum	ContrastEnhancementAlgorithm { NoEnhancement, StretchToMinimumMaximum, StretchAndClipToMinimumMaximum, ClipToMinimumMaximum, UserDefinedEnhancement }
	This enumerator describes the types of contrast enhancement algorithms that can be used. More...

Public Member Functions
	QgsContrastEnhancement (QGis::DataType theDatatype=QGis::Byte)
	QgsContrastEnhancement (const QgsContrastEnhancement &ce)
	~QgsContrastEnhancement ()
double	maximumValue () const
	Return the maximum value for the contrast enhancement range.
double	minimumValue () const
	Return the minimum value for the contrast enhancement range.
ContrastEnhancementAlgorithm	contrastEnhancementAlgorithm () const
int	enhanceContrast (double)
	Apply the contrast enhancement to a value.
bool	isValueInDisplayableRange (double)
	Return true if pixel is in stretable range, false if pixel is outside of range (i.e., clipped)
void	setContrastEnhancementAlgorithm (ContrastEnhancementAlgorithm, bool generateTable=true)
	Set the contrast enhancement algorithm.
void	setContrastEnhancementFunction (QgsContrastEnhancementFunction *)
	A public method that allows the user to set their own custom contrast enhancment function.
void	setMaximumValue (double, bool generateTable=true)
	Set the maximum value for the contrast enhancement range.
void	setMinimumValue (double, bool generateTable=true)
	Return the minimum value for the contrast enhancement range.
void	writeXML (QDomDocument &doc, QDomElement &parentElem) const
void	readXML (const QDomElement &elem)

Static Public Member Functions
static double	maximumValuePossible (QGis::DataType)
	Helper function that returns the maximum possible value for a GDAL data type.
static double	minimumValuePossible (QGis::DataType)
	Helper function that returns the minimum possible value for a GDAL data type.
static QString	contrastEnhancementAlgorithmString (ContrastEnhancementAlgorithm algorithm)
static ContrastEnhancementAlgorithm	contrastEnhancementAlgorithmFromString (const QString &contrastEnhancementString)

Private Member Functions
bool	generateLookupTable ()
	Method to generate a new lookup table.
int	calculateContrastEnhancementValue (double)
	Method to calculate the actual enhanceContrasted value(s)

Private Attributes
ContrastEnhancementAlgorithm	mContrastEnhancementAlgorithm
	Current contrast enhancement algorithm.
QgsContrastEnhancementFunction *	mContrastEnhancementFunction
	Pointer to the contrast enhancement function.
bool	mEnhancementDirty
	Flag indicating if the lookup table needs to be regenerated.
double	mLookupTableOffset
	Scalar so that values can be used as array indicies.
int *	mLookupTable
	Pointer to the lookup table.
double	mMinimumValue
	User defineable minimum value for the band, used for enhanceContrasting.
double	mMaximumValue
	user defineable maximum value for the band, used for enhanceContrasting
QGis::DataType	mRasterDataType
	Data type of the band.
double	mRasterDataTypeRange
	Maximum range of values for a given data type.

Detailed Description

Manipulates raster pixel values so that they enhanceContrast or clip into a specified numerical range according to the specified ContrastEnhancementAlgorithm.

Definition at line 38 of file qgscontrastenhancement.h.

Member Enumeration Documentation

enum QgsContrastEnhancement::ContrastEnhancementAlgorithm

This enumerator describes the types of contrast enhancement algorithms that can be used.

Enumerator:

NoEnhancement
StretchToMinimumMaximum
StretchAndClipToMinimumMaximum
ClipToMinimumMaximum
UserDefinedEnhancement

Definition at line 44 of file qgscontrastenhancement.h.

Constructor & Destructor Documentation

QgsContrastEnhancement::QgsContrastEnhancement ( QGis::DataType theDatatype = QGis::Byte )

Definition at line 31 of file qgscontrastenhancement.cpp.

References maximumValuePossible(), mContrastEnhancementAlgorithm, mContrastEnhancementFunction, mEnhancementDirty, minimumValuePossible(), mLookupTable, mLookupTableOffset, mMaximumValue, mMinimumValue, mRasterDataType, mRasterDataTypeRange, and NoEnhancement.

QgsContrastEnhancement::QgsContrastEnhancement ( const QgsContrastEnhancement & ce )

Definition at line 55 of file qgscontrastenhancement.cpp.

References mContrastEnhancementAlgorithm, mContrastEnhancementFunction, mEnhancementDirty, mLookupTable, mLookupTableOffset, mMaximumValue, mMinimumValue, mRasterDataType, mRasterDataTypeRange, and setContrastEnhancementAlgorithm().

QgsContrastEnhancement::~QgsContrastEnhancement ( )

Definition at line 78 of file qgscontrastenhancement.cpp.

References mContrastEnhancementFunction, and mLookupTable.

Member Function Documentation

int QgsContrastEnhancement::calculateContrastEnhancementValue ( double )

private

Method to calculate the actual enhanceContrasted value(s)

ContrastEnhancementAlgorithm QgsContrastEnhancement::contrastEnhancementAlgorithm ( ) const

inline

Definition at line 79 of file qgscontrastenhancement.h.

Referenced by QgsSingleBandGrayRenderer::legendSymbologyItems(), QgsSingleBandGrayRendererWidget::setFromRenderer(), and QgsMultiBandColorRendererWidget::setMinMaxValue().

QgsContrastEnhancement::ContrastEnhancementAlgorithm QgsContrastEnhancement::contrastEnhancementAlgorithmFromString ( const QString & contrastEnhancementString )

static

Definition at line 472 of file qgscontrastenhancement.cpp.

References ClipToMinimumMaximum, NoEnhancement, StretchAndClipToMinimumMaximum, StretchToMinimumMaximum, and UserDefinedEnhancement.

Referenced by readXML(), and QgsRasterLayer::setDefaultContrastEnhancement().

QString QgsContrastEnhancement::contrastEnhancementAlgorithmString ( ContrastEnhancementAlgorithm algorithm )

static

Definition at line 454 of file qgscontrastenhancement.cpp.

References ClipToMinimumMaximum, NoEnhancement, StretchAndClipToMinimumMaximum, StretchToMinimumMaximum, and UserDefinedEnhancement.

Referenced by writeXML().

int QgsContrastEnhancement::enhanceContrast ( double theValue )

Apply the contrast enhancement to a value.

Public function to generate the enhanced for enhanceContrasted value for a given input.

Return values are 0 - 254, -1 means the pixel was clipped and should not be displayed

Parameters

theValue The pixel value to enhance

Definition at line 198 of file qgscontrastenhancement.cpp.

References QgsContrastEnhancementFunction::enhance(), generateLookupTable(), mContrastEnhancementAlgorithm, mContrastEnhancementFunction, mEnhancementDirty, mLookupTable, mLookupTableOffset, and NoEnhancement.

Referenced by QgsMultiBandColorRenderer::block(), and QgsSingleBandGrayRenderer::block().

bool QgsContrastEnhancement::generateLookupTable ( )

private

Method to generate a new lookup table.

Generate a new lookup table.

Definition at line 221 of file qgscontrastenhancement.cpp.

References QGis::Byte, QgsContrastEnhancementFunction::enhance(), QGis::Int16, mContrastEnhancementAlgorithm, mContrastEnhancementFunction, mEnhancementDirty, mLookupTable, mLookupTableOffset, mMaximumValue, mMinimumValue, mRasterDataType, mRasterDataTypeRange, NoEnhancement, QgsDebugMsg, and QGis::UInt16.

Referenced by enhanceContrast(), setContrastEnhancementAlgorithm(), setContrastEnhancementFunction(), setMaximumValue(), and setMinimumValue().

bool QgsContrastEnhancement::isValueInDisplayableRange ( double theValue )

Return true if pixel is in stretable range, false if pixel is outside of range (i.e., clipped)

Determine if a pixel is within in the displayable range.

Parameters

theValue The pixel value to examine

Definition at line 253 of file qgscontrastenhancement.cpp.

References QgsContrastEnhancementFunction::isValueInDisplayableRange(), and mContrastEnhancementFunction.

Referenced by QgsMultiBandColorRenderer::block(), and QgsSingleBandGrayRenderer::block().

double QgsContrastEnhancement::maximumValue ( ) const

inline

Return the maximum value for the contrast enhancement range.

Definition at line 74 of file qgscontrastenhancement.h.

Referenced by QgsSingleBandGrayRenderer::legendSymbologyItems(), QgsSingleBandGrayRendererWidget::setFromRenderer(), and QgsMultiBandColorRendererWidget::setMinMaxValue().

double QgsContrastEnhancement::maximumValuePossible ( QGis::DataType theDataType )

static

Helper function that returns the maximum possible value for a GDAL data type.

Simple function to compute the maximum possible value for a data types.

Definition at line 92 of file qgscontrastenhancement.cpp.

References QGis::ARGB32, QGis::ARGB32_Premultiplied, QGis::Byte, QGis::CFloat32, QGis::CFloat64, QGis::CInt16, QGis::CInt32, QGis::Float32, QGis::Float64, QGis::Int16, QGis::Int32, MathUtils::max(), QGis::UInt16, QGis::UInt32, and QGis::UnknownDataType.

Referenced by QgsClipToMinMaxEnhancement::enhance(), QgsContrastEnhancementFunction::enhance(), QgsRasterHistogramWidget::histoAction(), QgsContrastEnhancementFunction::isValueInDisplayableRange(), QgsContrastEnhancement(), QgsContrastEnhancementFunction::setMaximumValue(), setMaximumValue(), and QgsRasterFileWriter::writeDataRaster().

double QgsContrastEnhancement::minimumValue ( ) const

inline

Return the minimum value for the contrast enhancement range.

Definition at line 77 of file qgscontrastenhancement.h.

Referenced by QgsSingleBandGrayRenderer::legendSymbologyItems(), QgsSingleBandGrayRendererWidget::setFromRenderer(), and QgsMultiBandColorRendererWidget::setMinMaxValue().

double QgsContrastEnhancement::minimumValuePossible ( QGis::DataType theDataType )

static

Helper function that returns the minimum possible value for a GDAL data type.

Simple function to compute the minimum possible value for a data type.

Definition at line 141 of file qgscontrastenhancement.cpp.

References QGis::ARGB32, QGis::ARGB32_Premultiplied, QGis::Byte, QGis::CFloat32, QGis::CFloat64, QGis::CInt16, QGis::CInt32, QGis::Float32, QGis::Float64, QGis::Int16, QGis::Int32, MathUtils::max(), MathUtils::min(), QGis::UInt16, QGis::UInt32, and QGis::UnknownDataType.

Referenced by QgsClipToMinMaxEnhancement::enhance(), QgsContrastEnhancementFunction::enhance(), QgsRasterHistogramWidget::histoAction(), QgsContrastEnhancementFunction::isValueInDisplayableRange(), QgsContrastEnhancement(), QgsContrastEnhancementFunction::setMinimumValue(), and setMinimumValue().

void QgsContrastEnhancement::readXML ( const QDomElement & elem )

Definition at line 407 of file qgscontrastenhancement.cpp.

References ClipToMinimumMaximum, contrastEnhancementAlgorithmFromString(), mMaximumValue, mMinimumValue, NoEnhancement, setContrastEnhancementAlgorithm(), StretchAndClipToMinimumMaximum, StretchToMinimumMaximum, and UserDefinedEnhancement.

Referenced by QgsMultiBandColorRenderer::create(), and QgsSingleBandGrayRenderer::create().

void QgsContrastEnhancement::setContrastEnhancementAlgorithm	(	ContrastEnhancementAlgorithm	theAlgorithm,
		bool	generateTable = `true`
	)

Set the contrast enhancement algorithm.

The second parameter is optional and is for performace improvements. If you know you are immediately going to set the Minimum or Maximum value, you can elect to not generate the lookup tale. By default it will be generated.

Parameters

theAlgorithm	The new contrast enhancement algorithm
generateTable	Flag to overide automatic look up table generation

Definition at line 270 of file qgscontrastenhancement.cpp.

References ClipToMinimumMaximum, generateLookupTable(), mContrastEnhancementAlgorithm, mContrastEnhancementFunction, mEnhancementDirty, mMaximumValue, mMinimumValue, mRasterDataType, QgsDebugMsg, StretchAndClipToMinimumMaximum, StretchToMinimumMaximum, and UserDefinedEnhancement.

Referenced by QgsContrastEnhancement(), readXML(), QgsSingleBandGrayRendererWidget::renderer(), QgsRasterLayer::setContrastEnhancement(), and QgsMultiBandColorRendererWidget::setCustomMinMaxValues().

void QgsContrastEnhancement::setContrastEnhancementFunction ( QgsContrastEnhancementFunction * theFunction )

A public method that allows the user to set their own custom contrast enhancment function.

A public function that allows the user to set their own custom contrast enhancement function.

Parameters

theFunction The new contrast enhancement function

Definition at line 310 of file qgscontrastenhancement.cpp.

References generateLookupTable(), mContrastEnhancementAlgorithm, mContrastEnhancementFunction, QgsDebugMsg, and UserDefinedEnhancement.

void QgsContrastEnhancement::setMaximumValue	(	double	theValue,
		bool	generateTable = `true`
	)

Set the maximum value for the contrast enhancement range.

Set the maximum value for the contrast enhancement.

The second parameter is option an is for performace improvements. If you know you are immediately going to set the Minimum value or the contrast enhancement algorithm, you can elect to not generate the lookup tale. By default it will be generated.

Parameters

theValue	The new maximum value for the band
generateTable	Flag to overide automatic look up table generation

Definition at line 328 of file qgscontrastenhancement.cpp.

References generateLookupTable(), maximumValuePossible(), mContrastEnhancementFunction, mEnhancementDirty, mMaximumValue, mRasterDataType, QgsDebugMsg, and QgsContrastEnhancementFunction::setMaximumValue().

Referenced by QgsSingleBandGrayRendererWidget::renderer(), QgsRasterLayer::setContrastEnhancement(), and QgsMultiBandColorRendererWidget::setCustomMinMaxValues().

void QgsContrastEnhancement::setMinimumValue	(	double	theValue,
		bool	generateTable = `true`
	)

Return the minimum value for the contrast enhancement range.

Set the maximum value for the contrast enhancement.

The second parameter is option an is for performace improvements. If you know you are immediately going to set the Maximum value or the contrast enhancement algorithm, you can elect to not generate the lookup tale. By default it will be generated.

Parameters