Package net.sourceforge.jiu.color.dithering

Class ClusteredDotDither

java.lang.Object
net.sourceforge.jiu.ops.Operation
net.sourceforge.jiu.ops.ImageToImageOperation
net.sourceforge.jiu.color.dithering.ClusteredDotDither
public class ClusteredDotDither extends ImageToImageOperation
Apply a clustered dot ordered dither to a grayscale image, converting it to a bilevel image in the process. Works with GrayIntegerImage objects as input and BilevelImage objects as output. Resolution of both must be the same. Use one of the predefined dither matrices or have one compiled from a spot function (given by an object of a class implementing SpotFunction). There are a couple of classes implementing that spot function interface in the dithering package. If no matrix is specified, process() creates a default matrix by calling setOrder3DitherMatrix().

Usage example

 ClusteredDotDither dither = new ClusteredDotDither();
 dither.setInputImage(image); // some GrayIntegerImage
 dither.setDitherMatrix(8, 8, new DiamondSpotFunction());
 dither.process();
 PixelImage ditheredImage = dither.getOutputImage();

Credits

The predefined dither matrices were taken from Netpbm's pgmtopbm program (the matrices are stored in the file dithers.h).

I learned about spot functions and their use from Austin Donnelly's GIMP plugin newsprint - it has extensive comments, and the newsprint website explains the theoretical background.

Since:
0.9.0
Author:
Marco Schmidt

  • Field Details

    • ditherHeight

      private int ditherHeight

    • ditherWidth

      private int ditherWidth

    • ditherData

      private int[] ditherData

  • Constructor Details

    • ClusteredDotDither

      public ClusteredDotDither()

  • Method Details

    • process

      public void process() throws MissingParameterException, WrongParameterException
      Description copied from class: Operation
      This method does the actual work of the operation. It must be called after all parameters have been given to the operation object.
      Overrides:
      process in class Operation
      Throws:
      MissingParameterException - if any mandatory parameter was not given to the operation
      WrongParameterException - if at least one of the input parameters was not initialized appropriately (values out of the valid interval, etc.)

    • process

      private void process(GrayIntegerImage in, BilevelImage out)

    • setDefaults

      private void setDefaults()

    • setDitherMatrix

      public void setDitherMatrix(int width, int height, int[] data)
      Sets the dither matrix to be used in this operation.
      Parameters:
      width - number of entries in horizontal direction
      height - number of entries in vertical direction
      data - matrix entries, in order top to bottom, and in each row left to right
      Throws:
      IllegalArgumentException - if width or height are smaller than one or data is null or has not at least width times height entries

    • setDitherMatrix

      public void setDitherMatrix(int width, int height, SpotFunction f)
      Creates and sets a dither matrix of user-defined size and compiles it from a spot function. Creates a matrix from the spot function and calls setDitherMatrix(int, int, int[]).
      Parameters:
      width - width of matrix, must be one or larger
      height - height of matrix, must be one or larger
      f - the spot function to be used for compiling the matrix

    • setOrder3DitherMatrix

      public void setOrder3DitherMatrix()
      Sets a 6 times 6 elements matrix to be used for dithering.

    • setOrder4DitherMatrix

      public void setOrder4DitherMatrix()
      Sets an 8 times 8 elements matrix to be used for dithering.

    • setOrder8DitherMatrix

      public void setOrder8DitherMatrix()
      Sets a 16 times 16 elements matrix to be used for dithering.