[Chapter 22] RGBImageFilter
Author: John Zukowski
Date: Thu Jul 31 15:25:58 1997

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| Chapter 22 java.awt.image Reference |

# RGBImageFilter

## Name

RGBImageFilter

##

## Description

`RGBImageFilter` is an abstract class that helps you filter images based on each pixel's color and position. In most cases, the only method you need to implement in subclasses is `filterRGB()`, which returns a new pixel value based on the old pixel's color and position. `RGBImageFilter` cannot be used to implement filters that depend on the value of neighboring pixels, or other factors aside from color and position.

## Class Definition

    public abstract class java.awt.image.RGBImageFilter
        extends java.awt.image.ImageFilter {
      // Variables
      protected boolean canFilterIndexColorModel;
      protected ColorModel newmodel;
      protected ColorModel oldmodel;
      // Instance Methods
      public IndexColorModel filterIndexColorModel (IndexColorModel icm);
      public abstract int filterRGB (int x, int y, int rgb);
      public void filterRGBPixels (int x, int y, int width,
          int height, int[] pixels, int off, int scansize);
      public void setColorModel (ColorModel model);
      public void setPixels (int x, int y, int width, int height,
          ColorModel model, byte[] pixels, int offset, int scansize);
      public void setPixels (int x, int y, int width, int height,
          ColorModel model, int[] pixels, int offset, int scansize);
      public void substituteColorModel (ColorModel oldModel,
          ColorModel newModel);
    }

## Variables

### canFilterIndexColorModel

#### protected boolean canFilterIndexColorModel

Setting the `canFilterIndexColorModel` variable to `true` indicates the filter can filter `IndexColorModel` images. To filter an `IndexColorModel`, the filter must depend only on color, not on position.

### newmodel

#### protected ColorModel newmodel

A place to store a new `ColorModel`.

### origmodel

#### protected ColorModel origmodel

A place to store an old `ColorModel`.

## Instance Methods

### filterIndexColorModel

#### public IndexColorModel filterIndexColorModel (IndexColorModel icm)

Parameters

  icm

    Color model to filter.

Returns

  Filtered color model.

Description

  Helper method for `setColorModel()` that runs the entire color table of `icm` through the `filterRGB()` method of the subclass. Used only if `canFilterIndexColorModel` is `true`, and the image uses an `IndexColorModel`.

### filterRGB

#### public abstract int filterRGB (int x, int y, int rgb)

Parameters

  x

    x-coordinate of pixel data.

  y

    y-coordinate of pixel data.

  rgb

    Color value of pixel to filter.

Returns

  New color value of pixel.

Description

  Subclasses implement this method to provide a filtering function that generates new pixels.

### filterRGBPixels

#### public void filterRGBPixels (int x, int y, int width, int height, int[] pixels, int off, int scansize)

Parameters

  x

    x-coordinate of top-left corner of pixel data within entire image.

  y

    y-coordinate of top-left corner of pixel data within entire image.

  width

    Width of pixel data within entire image.

  height

    Height of pixel data within entire image.

  pixels

    Image data.

  off

    Offset from beginning of each line in pixels array.

  scansize

    Size of each line of data in pixels array.

Description

  Helper method for `setPixels()` that filters each element of the `pixels` buffer through the subclass's `filterRGB()` method.

### setColorModel

#### public void setColorModel (ColorModel model)

Parameters

  model

    The color model for the image.

Overrides

  `ImageFilter.setColorModel(``ColorModel``)`

Description

  Sets the image's color model.

### setPixels

#### public void setPixels (int x, int y, int width, int height, ColorModel model, byte[] pixels, int offset, int scansize)

Parameters

  x

    x-coordinate of top-left corner of pixel data delivered with this method call.

  y

    y-coordinate of top-left corner of pixel data delivered with this method call.

  width

    Width of the rectangle of pixel data delivered with this method call.

  height

    Height of the rectangle of pixel data delivered with this method call.

  model

    Color model of image data.

  pixels

    Image data.

  offset

    Offset from beginning of the pixels array.

  scansize

    Size of each line of data in pixels array.

Overrides

  `ImageFilter.setPixels(``int, int, int, int, ColorModel, byte[], int, int``)`

Description

  Called by the `ImageProducer` to deliver a rectangular block of pixels for filtering.

#### public void setPixels (int x, int y, int width, int height, ColorModel model, int[] pixels, int offset, int scansize)

Parameters

  x

    x-coordinate of top-left corner of pixel data delivered with this method call.

  y

    y-coordinate of top-left corner of pixel data delivered with this method call.

  width

    Width of the rectangle of pixel data delivered with this method call.

  height

    Height of the rectangle of pixel data delivered with this method call.

  model

    Color model of image data.

  pixels

    Image data.

  offset

    Offset from beginning of the pixels array.

  scansize

    Size of each line of data in pixels array.

Overrides

  `ImageFilter.setPixels(``int, int, int, int, ColorModel, int[], int, int``)`

Description

  Called by the `ImageProducer` to deliver a rectangular block of pixels for filtering.

### substituteColorModel

#### public void substituteColorModel (ColorModel oldModel, ColorModel newModel)

Parameters

  oldModel

    New value for `origmodel` variable.

  newModel

    New value for `newmodel` variable.

Description

  Helper method for `setColorModel()` to initialize the protected variables `newmodel` and `origmodel`.

## See Also

`ColorModel`, `ImageFilter`

ReplicateScaleFilter |  | java.awt.peer Reference