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5.7 ColorModels and Color Data

In addition to the Raster object for managing image data, the BufferedImage class includes a ColorModel for interpreting that data as color pixel values. The abstract ColorModel class defines methods for turning an image's pixel data into a color value in its associated ColorSpace.

The java.awt.image package provides four types of color models:

• PackedColorModel--An abstract ColorModel that represents pixel values that have color components embedded directly in the bits of an integer pixel. A DirectColorModel is a subclass of PackedColorModel.
• DirectColorModel--a ColorModel that represents pixel values that have RGB color components embedded directly in the bits of the pixel itself. DirectColorModel model is similar to an X11 TrueColor visual.
• ComponentColorModel--a ColorModel that can handle an arbitrary ColorSpace and an array of color components to match the ColorSpace.
• IndexColorModel--a ColorModel that represents pixel values that are indices into a fixed color map in the sRGB color space.

ComponentColorModel and PackedColorModel are new in the Java^TM 2 SDK software release.

Based on data in the DataBuffer, the SampleModel provides the ColorModel with a pixel, which the ColorModel then interprets as a color.

5.7.1 Lookup Table

A lookup table contains data for one or more channels or image components; for example, separate arrays for R, G, and B. The java.awt.image package defines two types of lookup tables that extend the abstract LookupTable class, one that contains byte data and one that contains short data (ByteLookupTable and ShortLookupData).