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. clipped).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 ¶
- Return type:
- 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) –