QgsContrastEnhancement Class Reference

Handles contrast enhancement and clipping. More...

#include <qgscontrastenhancement.h>

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 (const QgsContrastEnhancement &ce)
	QgsContrastEnhancement (Qgis::DataType datatype=Qgis::DataType::Byte)
	Constructor for QgsContrastEnhancement, for the specified data type.
	~QgsContrastEnhancement ()
ContrastEnhancementAlgorithm	contrastEnhancementAlgorithm () const
int	enhanceContrast (double value)
	Applies the contrast enhancement to a value.
bool	isValueInDisplayableRange (double value)
	Returns true if a pixel value is in displayable range, false if pixel is outside of range (i.e.
double	maximumValue () const
	Returns the maximum value for the contrast enhancement range.
double	minimumValue () const
	Returns the minimum value for the contrast enhancement range.
const QgsContrastEnhancement &	operator= (const QgsContrastEnhancement &)=delete
void	readXml (const QDomElement &elem)
void	setContrastEnhancementAlgorithm (ContrastEnhancementAlgorithm algorithm, bool generateTable=true)
	Sets the contrast enhancement algorithm.
void	setContrastEnhancementFunction (QgsContrastEnhancementFunction *function)
	Allows the user to set their own custom contrast enhancement function.
void	setMaximumValue (double value, bool generateTable=true)
	Sets the maximum value for the contrast enhancement range.
void	setMinimumValue (double value, bool generateTable=true)
	Sets the minimum value for the contrast enhancement range.
void	toSld (QDomDocument &doc, QDomElement &element) const
	Write ContrastEnhancement tags following SLD v1.0 specs SLD1.0 is limited to the parameters listed in: https://docs.geoserver.org/stable/en/user/styling/sld/reference/rastersymbolizer.html#contrastenhancement Btw only sld:Normalize + vendor options are supported because there is no clear mapping of ContrastEnhancement parameters to support sld:Histogram or sld:GammaValue.
void	writeXml (QDomDocument &doc, QDomElement &parentElem) const

Static Public Member Functions
static ContrastEnhancementAlgorithm	contrastEnhancementAlgorithmFromString (const QString &contrastEnhancementString)
	Deserialize ContrastEnhancementAlgorithm.
static QString	contrastEnhancementAlgorithmString (ContrastEnhancementAlgorithm algorithm)
	Returns a string to serialize ContrastEnhancementAlgorithm.
static double	maximumValuePossible (Qgis::DataType dataType)
	Helper function that returns the maximum possible value for a data type.
static double	minimumValuePossible (Qgis::DataType dataType)
	Helper function that returns the minimum possible value for a data type.

Detailed Description

Handles contrast enhancement and clipping.

Manipulates raster or point cloud pixel values so that they enhance contrast or clip into a specified numerical range according to the specified ContrastEnhancementAlgorithm.

Definition at line 44 of file qgscontrastenhancement.h.

Member Enumeration Documentation

ContrastEnhancementAlgorithm

enum QgsContrastEnhancement::ContrastEnhancementAlgorithm

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

Enumerator
NoEnhancement	Default color scaling algorithm, no scaling is applied.
StretchToMinimumMaximum	Linear histogram.
StretchAndClipToMinimumMaximum
ClipToMinimumMaximum
UserDefinedEnhancement

Definition at line 50 of file qgscontrastenhancement.h.

Constructor & Destructor Documentation

QgsContrastEnhancement() [1/2]

QgsContrastEnhancement::QgsContrastEnhancement

(

Qgis::DataType

datatype = Qgis::DataType::Byte

)

Constructor for QgsContrastEnhancement, for the specified data type.

Definition at line 35 of file qgscontrastenhancement.cpp.

QgsContrastEnhancement() [2/2]

QgsContrastEnhancement::QgsContrastEnhancement

(

const QgsContrastEnhancement &

ce

)

Definition at line 51 of file qgscontrastenhancement.cpp.

~QgsContrastEnhancement()

QgsContrastEnhancement::~QgsContrastEnhancement

(

)

Definition at line 70 of file qgscontrastenhancement.cpp.

Member Function Documentation

contrastEnhancementAlgorithm()

ContrastEnhancementAlgorithm QgsContrastEnhancement::contrastEnhancementAlgorithm ( ) const

inline

Definition at line 166 of file qgscontrastenhancement.h.

contrastEnhancementAlgorithmFromString()

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

static

Deserialize ContrastEnhancementAlgorithm.

Definition at line 385 of file qgscontrastenhancement.cpp.

contrastEnhancementAlgorithmString()

QString QgsContrastEnhancement::contrastEnhancementAlgorithmString ( ContrastEnhancementAlgorithm algorithm )

static

Returns a string to serialize ContrastEnhancementAlgorithm.

Definition at line 367 of file qgscontrastenhancement.cpp.

enhanceContrast()

int QgsContrastEnhancement::enhanceContrast

(

double

value

)

Applies the contrast enhancement to a value.

Return values are 0 - 255, -1 means the pixel was clipped and should not be displayed.

Definition at line 75 of file qgscontrastenhancement.cpp.

isValueInDisplayableRange()

bool QgsContrastEnhancement::isValueInDisplayableRange

(

double

value

)

Returns true if a pixel value is in displayable range, false if pixel is outside of range (i.e.

clipped).

Definition at line 146 of file qgscontrastenhancement.cpp.

maximumValue()

double QgsContrastEnhancement::maximumValue ( ) const

inline

Returns the maximum value for the contrast enhancement range.

Definition at line 161 of file qgscontrastenhancement.h.

maximumValuePossible()

double QgsContrastEnhancement::maximumValuePossible ( Qgis::DataType dataType )

inlinestatic

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

Definition at line 71 of file qgscontrastenhancement.h.

minimumValue()

double QgsContrastEnhancement::minimumValue ( ) const

inline

Returns the minimum value for the contrast enhancement range.

Definition at line 164 of file qgscontrastenhancement.h.

minimumValuePossible()

double QgsContrastEnhancement::minimumValuePossible ( Qgis::DataType dataType )

inlinestatic

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

Definition at line 112 of file qgscontrastenhancement.h.

operator=()

const QgsContrastEnhancement & QgsContrastEnhancement::operator= ( const QgsContrastEnhancement & )

delete

readXml()

void QgsContrastEnhancement::readXml

(

const QDomElement &

elem

)

Definition at line 271 of file qgscontrastenhancement.cpp.

setContrastEnhancementAlgorithm()

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

Sets the contrast enhancement algorithm.

The generateTable parameter is optional and is for performance 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.

Definition at line 156 of file qgscontrastenhancement.cpp.

setContrastEnhancementFunction()

void QgsContrastEnhancement::setContrastEnhancementFunction

(

QgsContrastEnhancementFunction *

function

)

Allows the user to set their own custom contrast enhancement function.

Ownership of function is transferred.

Definition at line 186 of file qgscontrastenhancement.cpp.

setMaximumValue()

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

Sets the maximum value for the contrast enhancement range.

The generateTable parameter is optional and is for performance 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 table. By default it will be generated.

See also

setMinimumValue()

Definition at line 198 of file qgscontrastenhancement.cpp.

setMinimumValue()

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

Sets the minimum value for the contrast enhancement range.

The generateTable parameter is optional and is for performance 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 table. By default it will be generated.

See also

setMaximumValue()

Definition at line 224 of file qgscontrastenhancement.cpp.

toSld()

void QgsContrastEnhancement::toSld	(	QDomDocument &	doc,
		QDomElement &	element ) const

Write ContrastEnhancement tags following SLD v1.0 specs SLD1.0 is limited to the parameters listed in: https://docs.geoserver.org/stable/en/user/styling/sld/reference/rastersymbolizer.html#contrastenhancement Btw only sld:Normalize + vendor options are supported because there is no clear mapping of ContrastEnhancement parameters to support sld:Histogram or sld:GammaValue.

Since

QGIS 3.6

Definition at line 318 of file qgscontrastenhancement.cpp.

writeXml()

void QgsContrastEnhancement::writeXml	(	QDomDocument &	doc,
		QDomElement &	parentElem ) const

Definition at line 250 of file qgscontrastenhancement.cpp.

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The documentation for this class was generated from the following files:

• /build/qgis-3.99.0+git20251210+2fe06baccd8+99sid/src/core/raster/qgscontrastenhancement.h
• /build/qgis-3.99.0+git20251210+2fe06baccd8+99sid/src/core/raster/qgscontrastenhancement.cpp