org.geotools.styling

Interface ContrastEnhancement

All Superinterfaces:

ContrastEnhancement

public interface ContrastEnhancement
extends ContrastEnhancement

The ContrastEnhancement object defines contrast enhancement for a channel of a false-color image or for a color image. Its format is:

 <xs:element name="ContrastEnhancement">
   <xs:complexType>
     <xs:sequence>
       <xs:choice minOccurs="0">
         <xs:element ref="sld:Normalize"/>
         <xs:element ref="sld:Histogram"/>
       </xs:choice>
       <xs:element ref="sld:GammaValue" minOccurs="0"/>
     </xs:sequence>
   </xs:complexType>
 </xs:element>
 <xs:element name="Normalize">
   <xs:complexType/>
 </xs:element>
 <xs:element name="Histogram">
   <xs:complexType/>
 </xs:element>
 <xs:element name="GammaValue" type="xs:double"/>
 

In the case of a color image, the relative grayscale brightness of a pixel color is used. ?Normalize? means to stretch the contrast so that the dimmest color is stretched to black and the brightest color is stretched to white, with all colors in between stretched out linearly. ?Histogram? means to stretch the contrast based on a histogram of how many colors are at each brightness level on input, with the goal of producing equal number of pixels in the image at each brightness level on output. This has the effect of revealing many subtle ground features. A ?GammaValue? tells how much to brighten (value greater than 1.0) or dim (value less than 1.0) an image. The default GammaValue is 1.0 (no change). If none of Normalize, Histogram, or GammaValue are selected in a ContrastEnhancement, then no enhancement is performed.

Author:

iant

Method Summary

Modifier and Type	Method and Description
void	accept(StyleVisitor visitor) Traversal of the style data structure.
void	addOption(String key, Expression value) Store a vendor option
Expression	getGammaValue() How much to brighten (values greater than 1.0) or dim (values less than 1.0) an image.
Expression	getOption(String string)
Map<String,Expression>	getOptions() Return vendor options relating to the enhancement method
boolean	hasOption(String key) check if vendor option key is available
void	setGammaValue(Expression gamma)
void	setMethod(ContrastMethod method) Used to set the contrast enhancement method used.
void	setMethod(ContrastMethodStrategy method) Convenience method to allow users to pass in a ContrastEnhancementMethod to update Method and Options in one go.
void	setOptions(Map<String,Expression> options)

Methods inherited from interface ContrastEnhancement

accept, getMethod

Method Detail

setMethod

void setMethod(ContrastMethod method)

Used to set the contrast enhancement method used.

Parameters:

method -

setGammaValue

void setGammaValue(Expression gamma)

Parameters:

gamma - How much to brighten (greater than 1) or dim (less than 1) this channel; use 1.0 to indicate no change.

getGammaValue

Expression getGammaValue()

How much to brighten (values greater than 1.0) or dim (values less than 1.0) an image. The default GammaValue is 1.0 (no change).

Specified by:

getGammaValue in interface ContrastEnhancement

Returns:

Expression, if null a value of 1.0 is assumed indicating no change

getOptions

Map<String,Expression> getOptions()

Return vendor options relating to the enhancement method

Returns:

a Map containing expressions with string keys.

hasOption

boolean hasOption(String key)

check if vendor option key is available

Parameters:

key - - the name of the option to check

Returns:

true if present

addOption

void addOption(String key,
               Expression value)

Store a vendor option

Parameters:

key - - the name of the option

value - an expression that evaluates to it's value

accept

void accept(StyleVisitor visitor)

Traversal of the style data structure.

Parameters:

visitor -

setOptions

void setOptions(Map<String,Expression> options)

Parameters:

options - a Map of VendorOptions

getOption

Expression getOption(String string)

Parameters:

string -

Returns:

An expression for the matching VendorOption

setMethod

void setMethod(ContrastMethodStrategy method)

Convenience method to allow users to pass in a ContrastEnhancementMethod to update Method and Options in one go.

Parameters:

method - the ContrastEnhancementMethod that underlies this enhancement