Class: QgsContrastEnhancement¶
- class qgis.core.QgsContrastEnhancement¶
Bases:
sip.wrapper
Manipulates raster or point cloud pixel values so that they enhanceContrast or clip into a specified numerical range according to the specified ContrastEnhancementAlgorithm.
QgsContrastEnhancement(datatype: Qgis.DataType = Qgis.DataType.Byte) Constructor for
QgsContrastEnhancement
, for the specified data type.QgsContrastEnhancement(ce:
QgsContrastEnhancement
)Methods
- rtype
QgsContrastEnhancement.ContrastEnhancementAlgorithm
Deserialize ContrastEnhancementAlgorithm.
Returns a string to serialize ContrastEnhancementAlgorithm.
Applies the contrast enhancement to a
value
.Returns
True
if a pixelvalue
is in displayable range,False
if pixel is outside of range (i.e.Returns the maximum value for the contrast enhancement range.
Helper function that returns the maximum possible value for a data type.
Returns the minimum value for the contrast enhancement range.
Helper function that returns the minimum possible value for a data type.
- param elem
Sets the contrast enhancement
algorithm
.Allows the user to set their own custom contrast enhancement
function
.Sets the maximum
value
for the contrast enhancement range.Sets the minimum
value
for the contrast enhancement range.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
- param doc
Attributes
- 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.
- Parameters
contrastEnhancementString (str) –
- Return type
- contrastEnhancementAlgorithmString(algorithm: QgsContrastEnhancement.ContrastEnhancementAlgorithm) str ¶
Returns a string to serialize ContrastEnhancementAlgorithm.
- Parameters
algorithm (QgsContrastEnhancement.ContrastEnhancementAlgorithm) –
- Return type
str
- 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.- Parameters
value (float) –
- Return type
int
- isValueInDisplayableRange(self, value: float) bool ¶
Returns
True
if a pixelvalue
is in displayable range,False
if pixel is outside of range (i.e. clipped).- Parameters
value (float) –
- Return type
bool
- maximumValue(self) float ¶
Returns the maximum value for the contrast enhancement range.
- Return type
float
- maximumValuePossible(dataType: Qgis.DataType) float ¶
Helper function that returns the maximum possible value for a data type.
- Parameters
dataType (Qgis.DataType) –
- Return type
float
- minimumValue(self) float ¶
Returns the minimum value for the contrast enhancement range.
- Return type
float
- minimumValuePossible(dataType: Qgis.DataType) float ¶
Helper function that returns the minimum possible value for a data type.
- Parameters
dataType (Qgis.DataType) –
- Return type
float
- readXml(self, elem: QDomElement)¶
- Parameters
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.- Parameters
algorithm (QgsContrastEnhancement.ContrastEnhancementAlgorithm) –
generateTable (bool = True) –
- setContrastEnhancementFunction(self, function: QgsContrastEnhancementFunction)¶
Allows the user to set their own custom contrast enhancement
function
. Ownership offunction
is transferred.- Parameters
function (QgsContrastEnhancementFunction) –
- 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.See also
- Parameters
value (float) –
generateTable (bool = True) –
- 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.See also
- Parameters
value (float) –
generateTable (bool = True) –
- 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.
- Parameters
doc (QDomDocument) –
element (QDomElement) –
- writeXml(self, doc: QDomDocument, parentElem: QDomElement)¶
- Parameters
doc (QDomDocument) –
parentElem (QDomElement) –