Class: QgsContrastEnhancement¶

class qgis.core.QgsContrastEnhancement¶

Bases: sip.wrapper

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

Enums

Methods

contrastEnhancementAlgorithm

contrastEnhancementAlgorithmFromString

Deserialize ContrastEnhancementAlgorithm.

contrastEnhancementAlgorithmString

Returns a string to serialize ContrastEnhancementAlgorithm.

enhanceContrast

Applies the contrast enhancement to a value.

isValueInDisplayableRange

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

maximumValue

Returns the maximum value for the contrast enhancement range.

maximumValuePossible

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

minimumValue

Returns the minimum value for the contrast enhancement range.

minimumValuePossible

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

readXml

setContrastEnhancementAlgorithm

Sets the contrast enhancement algorithm.

setContrastEnhancementFunction

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

setMaximumValue

Sets the maximum value for the contrast enhancement range.

setMinimumValue

Sets the minimum value for the contrast enhancement range.

toSld

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

writeXml

Signals

Attributes

ClipToMinimumMaximum

NoEnhancement

StretchAndClipToMinimumMaximum

StretchToMinimumMaximum

UserDefinedEnhancement

ClipToMinimumMaximum = 3¶

class ContrastEnhancementAlgorithm¶: Bases: int

NoEnhancement = 0¶

StretchAndClipToMinimumMaximum = 2¶

StretchToMinimumMaximum = 1¶

UserDefinedEnhancement = 4¶

contrastEnhancementAlgorithm(self) → QgsContrastEnhancement.ContrastEnhancementAlgorithm¶

contrastEnhancementAlgorithmFromString(contrastEnhancementString: str) → QgsContrastEnhancement.ContrastEnhancementAlgorithm¶: Deserialize ContrastEnhancementAlgorithm.

contrastEnhancementAlgorithmString(algorithm: QgsContrastEnhancement.ContrastEnhancementAlgorithm) → str¶: Returns a string to serialize ContrastEnhancementAlgorithm.

enhanceContrast(self, value: float) → int¶: Applies the contrast enhancement to a value. Return values are 0 - 254, -1 means the pixel was clipped and should not be displayed.

isValueInDisplayableRange(self, value: float) → bool¶: Returns True if a pixel value is in displayable range, False if pixel is outside of range (i.e. clipped).

maximumValue(self) → float¶: Returns the maximum value for the contrast enhancement range.

maximumValuePossible(Qgis.DataType) → float¶: Helper function that returns the maximum possible value for a GDAL data type.

minimumValue(self) → float¶: Returns the minimum value for the contrast enhancement range.

minimumValuePossible(Qgis.DataType) → float¶: Helper function that returns the minimum possible value for a GDAL data type.

readXml(self, elem: QDomElement)¶

setContrastEnhancementAlgorithm(self, algorithm: QgsContrastEnhancement.ContrastEnhancementAlgorithm, generateTable: bool = 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.

setContrastEnhancementFunction(self, function: QgsContrastEnhancementFunction)¶: Allows the user to set their own custom contrast enhancement function. Ownership of function is transferred.

setMaximumValue(self, value: float, generateTable: bool = 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.