Package org.geotools.api.style

Interface ContrastEnhancement

All Known Implementing Classes:
ContrastEnhancementImpl
public interface ContrastEnhancement
The ContrastEnhancement object defines contrast enhancement for a channel of a false-color image or for a color image.

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.

Since:
GeoAPI 2.2
Author:
Open Geospatial Consortium, Ian Turton, CCG, Johann Sorel (Geomatys)

  • Method Details

    • getMethod

      ContrastMethod getMethod()
      We use a codeList to enable more enchancement type possibilities.

    • setMethod

      void setMethod(ContrastMethod method)
      Used to set the contrast enhancement method used.

    • 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).
      Returns:
      Expression, if null a value of 1.0 is assumed indicating no change

    • accept

      Object accept(TraversingStyleVisitor visitor, Object extraData)
      calls the visit method of a StyleVisitor
      Parameters:
      visitor - the style visitor

    • 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.

    • setOptions

      void setOptions(Map<String,Expression> options)
      Parameters:
      options - a Map of VendorOptions

    • getOption

      Expression getOption(String string)
      Returns:
      An expression for the matching VendorOption

    • setMethod

      void setMethod(ContrastMethodStrategy method)
      Convenience method to allow users to pass in a ContrastMethodStrategy to update setMethod(org.geotools.api.style.ContrastMethod) and setOptions(java.util.Map<java.lang.String, org.geotools.api.filter.expression.Expression>) in one go.
      Parameters:
      method - the ContrastMethodStrategy that underlies this enhancement