QgsContrastEnhancement Class Reference

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

Detailed Description

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

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

Constructor & Destructor Documentation

QgsContrastEnhancement::QgsContrastEnhancement

(

QGis::DataType

theDatatype = QGis::Byte

)

QgsContrastEnhancement::QgsContrastEnhancement

(

const QgsContrastEnhancement &

ce

)

QgsContrastEnhancement::~QgsContrastEnhancement

(

)

Member Function Documentation

ContrastEnhancementAlgorithm QgsContrastEnhancement::contrastEnhancementAlgorithm ( ) const

inline

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

static

QString QgsContrastEnhancement::contrastEnhancementAlgorithmString ( ContrastEnhancementAlgorithm  algorithm )

static

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

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

double QgsContrastEnhancement::maximumValue ( ) const

inline

Return the maximum value for the contrast enhancement range.

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.

double QgsContrastEnhancement::minimumValue ( ) const

inline

Return the minimum value for the contrast enhancement range.

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.

void QgsContrastEnhancement::readXML

(

const QDomElement &

elem

)

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

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

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

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

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

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

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

• /tmp/buildd/qgis-2.6.0+wheezy1/src/core/raster/qgscontrastenhancement.h
• /tmp/buildd/qgis-2.6.0+wheezy1/src/core/raster/qgscontrastenhancement.cpp