Class ArbitraryPaletteQuantizer

java.lang.Object
net.sourceforge.jiu.ops.Operation
net.sourceforge.jiu.ops.ImageToImageOperation
net.sourceforge.jiu.color.quantization.ArbitraryPaletteQuantizer
All Implemented Interfaces:
RGBQuantizer, RGBIndex

public class ArbitraryPaletteQuantizer extends ImageToImageOperation implements RGBIndex, RGBQuantizer
A color quantizer that maps an RGBImage to any given palette. This operation is restricted to RGB24Image and palettes with up to 256 colors. It picks the color from the palette which is closest to the color to be quantized (with the minimum distance). This is a rather naive implementation which, for any given color to be quantized, computes the distance between it and each color in the palette (read: this operation is rather slow with a large palette and input image).

It uses Manhattan distance (L1) instead of Euclidean distance (L2). This saves a square root operation per distance computation.

There are more sophisticated nearest neighbor algorithms available, left for future extensions.

Usage example

This example maps an RGB truecolor image to some palette we create.

 RGB24Image image = ...; // initialize this
 // create some Palette object that you want to map the image to
 Palette palette = new Palette(3); // create palette with three entries
 palette.put(0, 33, 00, 244); // set first color
 palette.put(1, 0, 240, 193); // set second color
 palette.put(2, 245, 126, 136); // set third color
 ArbitraryPaletteQuantizer quantizer = new ArbitraryPaletteQuantizer(palette);
 quantizer.setInputImage(image);
 quantizer.process();
 PixelImage quantizedImage = quantizer.getOutputImage();
 
Since:
0.5.0
Author:
Marco Schmidt
  • Field Details

    • RED

      private final int[] RED
    • GREEN

      private final int[] GREEN
    • BLUE

      private final int[] BLUE
    • palette

      private Palette palette
    • numEntries

      private int numEntries
  • Constructor Details

    • ArbitraryPaletteQuantizer

      public ArbitraryPaletteQuantizer(Palette palette)
      Creates a quantizer that will be able to map pixels (or a complete image) to the argument palette.
  • Method Details

    • createPalette

      public Palette createPalette()
      Returns a copy of the palette that was given to the constructor of this class.
      Specified by:
      createPalette in interface RGBQuantizer
      Returns:
      new copy of the palette this quantizer works on
    • map

      public int map(int[] origRgb, int[] quantizedRgb)
      Description copied from interface: RGBQuantizer
      This method maps a triplet of intensity values to its quantized counterpart and returns the palette index of that quantized color. The index values for the two arrays are taken from RGBIndex.
      Specified by:
      map in interface RGBQuantizer
      Parameters:
      origRgb - the three samples red, green and blue for which a good match is searched in the palette
      quantizedRgb - will hold the three samples found to be closest to origRgb after the call to this method
      Returns:
      int index in the palette of the match quantizedRgb
    • map

      public int map(int red, int green, int blue)
      Finds the best match for the argument color in the palette and returns its index. Similar to map(int[], int[]), the quantized color is not required and thus a few assignemnts are saved by this method.
      Parameters:
      red - red sample of the pixel to be quantized
      green - green sample of the pixel to be quantized
      blue - blue sample of the pixel to be quantized
      Returns:
      index of the color in the palette that is closest to the argument color
    • process

      private void process(RGB24Image in, Paletted8Image out)
    • process

      public void process() throws MissingParameterException, WrongParameterException
      Maps the input image to an output image, using the palette given to the constructor.
      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.)