QGIS API Documentation  2.6.0-Brighton
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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

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
theValueThe 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
theValueThe 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
theAlgorithmThe new contrast enhancement algorithm
generateTableFlag 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
theFunctionThe 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
theValueThe new maximum value for the band
generateTableFlag 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
theValueThe new minimum value for the band
generateTableFlag to overide automatic look up table generation
void QgsContrastEnhancement::writeXML ( QDomDocument &  doc,
QDomElement &  parentElem 
) const

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