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.

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

toSld(self, doc: QDomDocument, element: QDomElement)

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

New in version 3.6.

writeXml(self, doc: QDomDocument, parentElem: QDomElement)